Revision History

December 2024

2023 ACS 1-Year Summary File

December 5, 2024

The NHGIS data collection now includes the 2023 American Community Survey (ACS) 1-Year Summary File. Over 1,400 new tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

In the 1-year dataset, tables are available only for geographic areas with populations of at least 65,000.

For information about changes from earlier ACS Summary Files, see the Census Bureau's listing of Table Changes for 2023 ACS 1-Year Estimates.

NHGIS modifies the ACS data only to replace special negative and non-numeric values with blanks in the data columns. We do this to facilitate GIS processing.

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November 2024

Land Cover Summaries for More Levels & Years, Through 2021

November 11, 2024

NHGIS has released updated land cover summaries for 2010, 2020, and 2022-vintage census tracts, county subdivisions, counties, and places.

The land cover data come from the National Land Cover Database (NLCD), which is derived from 30-meter resolution Landsat imagery. The NLCD summaries identify the proportion of area covered by each of 16 land cover classes in 2001, 2004, 2006, 2008, 2011, 2013, 2016, 2019, and 2021.

This release expands our prior release of land cover summaries to include more geographic levels and more years of NLCD data.

This set of NHGIS land cover summaries is available in two file layouts: time varies by column and time varies by file.

For more information, or to download the files, see the Environmental Summaries resource page.

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October 2024

New Version Number & DOI

October 30, 2024

We have updated the version number and DOI for NHGIS, and the recommended citation is now:

Steven Manson, Jonathan Schroeder, David Van Riper, Katherine Knowles, Tracy Kugler, Finn Roberts, and Steven Ruggles. IPUMS National Historical Geographic Information System: Version 19.0 [dataset]. Minneapolis, MN: IPUMS. 2024. http://doi.org/10.18128/D050.V19.0

We have preserved an archival record for version 19 generated from the October 24, 2024, version of the NHGIS website, data, and metadata.

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Major Redesign of NHGIS Extract Engine

October 2, 2024

NHGIS has deployed a redesigned extract engine, replacing a system that had used an Apache Spark cluster-computing framework with a simpler Rust-based system operating on flat Apache Parquet data files.

This update greatly reduces processing time for most table data requests. UPDATE: Eight weeks after this release, we measured a 61% average reduction in processing times across all NHGIS data requests.

This update completes an overhaul that we had begun in May 2023 with Release 9.1 of time series tables, at which time we implemented the new framework only for nominally integrated time series tables.

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June 2024

Geographic Crosswalk Updates Including New Crosswalks from Census Tracts

June 25, 2024

A new release of NHGIS geographic crosswalks includes many updates:

• New crosswalks from census tracts to census tracts and to counties for all of the year pairings covered by NHGIS crosswalks (1990 to 2010, 2000 to 2010, 2010 to 2020, and 2020 to 2010)
• New crosswalks from blocks to block groups, to census tracts, and to counties for all of the same year pairings
• Extended crosswalks from 2000 to include Puerto Rico
• Note: NHGIS does not yet include 2000 summary tables for Puerto Rico. Users who wish to use the crosswalks to allocate 2000 data to 2010 census units would need to acquire the 2000 summary data for Puerto Rico from other sources.
• A consistent, larger set of interpolation weights for all non-block crosswalks (those from block group parts, block groups, or census tracts)
• The current set now includes separate weights for:
• Population
• Adult population
• Families
• Households
• Housing units
• Owner-occupied housing units
• Renter-occupied housing units
• To complete this set, we added weights to previously existing crosswalks for the following characteristics:
• Adult population in crosswalks from 1990 and 2000 block group parts
• Families in crosswalks fom 2020 block groups
• Owner-occupied and renter-occupied units in all non-block crosswalks
• A single generic README file for all crosswalks (replacing crosswalk-specific README files)
• A consistent system for field names and field ordering in all crosswalks, as specified in the new README file
• This update required the following field name changes in the block-to-block crosswalks:
• GJOIN#### → blk####gj (where #### is a year)
• GEOID#### → blk####ge (where #### is a year)
• PAREA_VIA_BLK00 → parea (in 1990 block crosswalks)
• PAREA → parea (in non-1990 block crosswalks)
• WEIGHT → weight
• All block-to-block crosswalks now include both GISJOIN and GEOID identifiers, replacing the previously distinct sets of crosswalks that included each type of identifier separately
• An area proportion ("parea") is included in all crosswalks
• Previously, the crosswalks from block group parts included no area proportion. The new area proportions for 1990 block group parts are approximate, based on the somewhat limited and imprecise spatial information we were able to gather for all the component levels that determine the complex boundaries of 1990 block group parts.
• All weights and area proportion values are given with exactly 10 decimal digits of precision (replacing various degrees of precision among previously available crosswalks)
• More robust and consistent protocol for generating weights where the specified denominator is zero
• In non-block crosswalks, if a zero denominator would cause a weight to be undefined, we now first try using a "backup" weight based on the sum of population and housing units, and if that would also result in a zero denominator, we use the area proportion
• For example, in the crosswalk from 2010 block groups to 2020 tracts, if a 2010 block group contains no families, it is not possible to compute a valid wt_fam using family counts. We compute wt_fam instead by using the sum of population and housing units, or, if that sum is also zero for the 2010 block group, we use the proportion of the 2010 block group's area in the 2020 tract

For more information, and to download the files, see the Geographic Crosswalks page.

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February 2024

1980 Block Boundaries, Version 4.0

February 27, 2024

NHGIS has released its fourth set of 1980 block boundary shapefiles (Version 4.0). This release adds 47 new metropolitan areas and completes 8 metros that were partially available in Version 3.0. The 1980 block boundaries now include the top 28 of the top 30 largest metro areas by 1980 population and complete coverage of New England. The statewide and nationwide shapefiles have been updated to include all new metropolitan areas. A complete list of currently available metropolitan areas is provided here.

Click below for a list of the newly added metro areas:

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December 2023

2022 ACS 5-Year Summary File, Time Series Extensions & GIS Boundary Files

December 14, 2023

2018-2022 ACS 5-Year Summary File

The 2018-2022 American Community Survey (ACS) 5-Year Summary File is now available on NHGIS. Over 1,100 tables offer detailed cross-tabulations on age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

Tables are available for 87 geographic levels, down to census tracts and block groups.

NHGIS separates this summary file into four datasets, each providing tables for a different set of geographic levels:

• 2018_2022_ACS5a: 5-Year Data [2018-2022, Block Groups & Larger Areas] – 409 tables
• 2018_2022_ACS5b: 5-Year Data [2018-2022, Tracts & Larger Areas] – 701 tables
• 2018_2022_ACS5c: 5-Year Data [2018-2022, Summary by Residence 1 Year Ago] – 38 tables
• 2018_2022_ACS5d: 5-Year Data [2018-2022, Summary by Place of Work] – 34 tables

Note: NHGIS converts all special negative values to blanks.

Time Series Release 9.2: Extensions to Include 2018-2022 ACS 5-Year Data

This release extends 115 nominally integrated time series tables to include 2018-2022 ACS 5-Year. These time series tables now cover 13 5-year periods from 2006-2010 through 2018-2022 in addition to decennial census years.

The release includes one additional change in the content of a time series table. We have added ten time series to Table D10. Foreign-Born Persons by Place of Birth, a table that provides time series for all unique foreign places of birth identified in any ACS 5-year data release since 2006-2010. The new time series provide population counts for these places of birth beginning with the 2018-2022 period (the first 5-year period for which ACS tables separately identified them):

• Asia--South Central Asia--Bhutan
• Asia--Western Asia--Azerbaijan
• Asia--Western Asia--Georgia
• Asia--Western Asia--United Arab Emirates
• Africa--Eastern Africa--Tanzania
• Africa--Northern Africa--Algeria
• Africa--Western Africa--Ivory Coast
• Africa--Western Africa--Togo
• Oceania--Marshall Islands
• Americas--Latin America--Caribbean--St. Lucia

2022 GIS Boundary Files

NHGIS has released 79 new GIS boundary files based on 2022 TIGER/Line Shapefiles. The new files correspond to the geographic units of 2022 American Community Survey data. The release includes nationwide files for 27 geographic levels and 52 state-specific files for block groups.

There are six geographic levels with data in the 2022 ACS Summary Files but with no corresponding 2022 TIGER/Line Shapefiles:

• Metropolitan Statistical Area/Micropolitan Statistical Area
• Metropolitan Division
• Combined Statistical Area
• New England City and Town Area
• New England City and Town Area Division
• Combined New England City and Town Area

The definitions of these levels used in 2022 ACS data matches with the definitions used in 2021 TIGER/Line Shapefiles: both use March 2020 OMB delineations. For these six levels, NHGIS associates 2021 shapefiles with both years 2021 and 2022, so NHGIS users who filter on the year 2022 or on 2022 ACS datasets will still see that valid corresonding shapefiles are available (though based on 2021 TIGER/Line Shapefiles).

New Topic Filter: Field of Degree

With this release, we have added a new option for filtering data by topic in the NHGIS Data Finder: Field of Degree.

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November 2023

2022 ACS 1-Year Summary File

November 30, 2023

The NHGIS data collection now includes the 2022 American Community Survey (ACS) 1-Year Summary File. Over 1,400 new tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

In the 1-year dataset, tables are available only for geographic areas with populations of at least 65,000.

For information about changes from earlier ACS Summary Files, see the Census Bureau's listing of Table Changes for 2022 ACS 1-Year Estimates.

NHGIS modifies the ACS data only to replace all special negative and non-numeric values with blanks in the data columns. We do this to facilitate GIS processing.

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October 2023

New Version Number & DOI

October 19, 2023

We have updated the version number and DOI for NHGIS, and the recommended citation is now:

Steven Manson, Jonathan Schroeder, David Van Riper, Katherine Knowles, Tracy Kugler, Finn Roberts, and Steven Ruggles. IPUMS National Historical Geographic Information System: Version 18.0 [dataset]. Minneapolis, MN: IPUMS. 2023. http://doi.org/10.18128/D050.V18.0

We have preserved an archival record for version 18 generated from the October 1, 2023, version of the NHGIS website, data, and metadata.

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September 2023

Filtering by Year Now Fully Distinguishes Year Ranges from Single Years

September 19, 2023

We have updated the data filtering protocols used by the NHGIS Data Finder, changing which source tables will appear to be available when a user has selected a filter for a single year.

Previously, if a user selected a filter for any single year that was also the release year of American Community Survey (ACS) data, tables from the corresponding multi-year ACS dataset(s) would also appear in the "Select Data" listing. Now, only tables that report data for the specific selected year will appear.

For example, previously, if a user selected filters for the single years 2010 and 2020, the Data Finder would show all available tables from the 2010 and 2020 Census and from the 2010 and 2020 ACS release years, including the 2006-2010 and 2016-2020 5-Year ACS datasets and the 2008-2010 3-Year ACS dataset.

Now, if 2010 and 2020 are the only year filters selected, the Data Finder will not show tables from any multi-year ACS datasets. It will instead show only tables that report 2010 or 2020 characteristics specifically, including tables from the 2010 and 2020 Census datasets and from the 2010 1-Year ACS dataset. (The Data Finder would also show tables from a 2020 1-Year ACS dataset when the year 2020 is selected, but NHGIS does not include 2020 1-Year ACS data because the Census Bureau released only a very limited set of experimentally designed 2020 1-year summary data due to the disruption of the COVID-19 pandemic.)

Users can still use the year filter to find tables from multi-year ACS datasets by specifically selecting the year range of interest. For example, to see all available tables from the 2016-2020 5-Year ACS datasets, a user could select a filter for the 2016-2020 5-year range.

2020 Census Demographic & Housing Characteristics File (DHC)

September 5, 2023

NHGIS has released all data from the 2020 Census Demographic and Housing Characteristics File (DHC). There are 249 tables providing summary data on age, sex, race & ethnicity, urban/rural status, household size and relationship, cohabiting and same-sex couples, housing tenure, and group quarters types.

The tables are available for 164 geographic levels down to census blocks.

NHGIS separates the 2020 DHC into three datasets, each providing tables for a different set of geographic levels:

• 2020_DHCa: DHC - P & H Tables [Blocks & Larger Areas] – 141 tables
• 2020_DHCb: DHC - PCT & HCT Tables [Tracts & Larger Areas] – 98 tables
• 2020_DHCc: DHC - PCO Tables (Group Quarters Population Only) [Counties & Larger Areas] – 10 tables

New & Revised GIS Boundary Files for 2020 & 2010 PUMAs & Urban Areas

September 5, 2023

NHGIS has released two new GIS boundary files representing 2020 Public Use Microdata Areas (PUMAs) and 2020 urban areas. The new files are based on additions the Census Bureau made to their 2020 TIGER/Line Shapefiles after the original release of those files.

The new boundary files take the place of two files that NHGIS had already released with labels indicating that they were "2020" PUMAs and urban areas. In fact, those files represented 2010 PUMAs and urban areas, which are the versions identified in the American Community Survey 2016-2020 5-year summary tables. We have renamed those two files in NHGIS to indicate that they represent 2010 PUMAs and urban areas with a 2020 TIGER/Line+ basis.

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May 2023

Corrections for Missing Data in Time Series Tables

May 25, 2023

We corrected system errors that had been causing missing data in some NHGIS time series tables. The errors were introduced on May 2, 2023, with Release 9.1 of time series tables.

The missing data occurred in nominally integrated time series tables for three geographic levels:

• Counties - No records for Alaska, Hawaii, Puerto Rico, and 27 historical territories
• Census tracts - No records for:
• GISJOIN identifiers from G1800910040900 to G3701290012009, including all or part of 20 states in alphabetical order from Indiana to North Carolina
• Alaska
• Puerto Rico
• Certain counties and county equivalents that did not exist for the entire period 1940-2021:
• La Paz County, Arizona
• Broomfield County, Colorado
• Miami-Dade County, Florida
• Oglala Lakota County County, South Dakota
• Bedford, Chesapeake, Emporia, Fairfax, Franklin, Lexington, Manassas, Manassas Park, Poquoson and Salem cities, Virginia
• County subdivisions - No records for certain counties and county equivalents that did not exist for the entire period 1970-2021:
• 20 county equivalents in Alaska
• Dade County, Florida
• Yellowstone National Park, Montana
• Oglala Lakota County and Washabaugh County, South Dakota
• Nansemond County, Clifton Forge City, and South Boston City, Virginia

Time Series Tables, Release 9.1

May 2, 2023

This release extends our collection of nominally integrated time series tables to include American Community Survey (ACS) data for all 5-year periods from 2006-2010 through 2017-2021. Previously, the tables included 5-year data only for two periods, 2008-2012 and 2015-2019. (One exceptional table provided counts of persons born in Yugoslavia for 2007-2011.)

We also added new functionality in the NHGIS Data Finder that enables users to select years for time series tables. Previously, NHGIS data files would include all available years for any requested time series tables.

The new extensions apply only to nominally integrated tables, not geographically standardized tables. In total, 116 tables are involved:

• 75 tables had included only two ACS 5-year periods (2008-2012 and 2015-2019) and now include 12 5-year periods, along with multiple census years
• 35 tables had included only decennial census data but now also include ACS data for 12 5-year periods
• These all cover "short-form subjects" such as age, race, household size, and tenure
• 5 tables are new:
• 2 tables provide median age down to the tract level. (The previously available median age tables go down to the county level.)
• 3 tables use the most detailed categories available in ACS tables for sex by age, foreign place of birth, and housing vacancy
• 1 table for persons born in Yugoslavia had included data for 2007-2011, the last period for which the ACS identified this category, and now also includes 2006-2010

This update includes two other revisions:

1. We revised the system for table "sequence" numbers. The first part of these numbers, the part preceding the decimal point, corresponds to the "tabulation type" (a particular summary statistic and cross-classification, such as Median Age by Sex). The numbers for tabulation types previously varied in length from 1 to 5 digits. They all now have exactly 3 digits. The actual ordering remains mostly unchanged.
2. We revised the source for 1970 Total Population counts to come from the 1970 Count 2 dataset instead of Count 4. Count 4 helpfully provided a single total population count, but omitted small places. Count 2 includes records for all places but provides no single total population count. We derive total population by summing all counts from the Household Relationship (NT4A, which includes all population both within and outside of households).

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April 2023

Annual Census Tract Population Estimates, 2000-2019

April 24, 2023

NHGIS has released annual census tract population estimates for 2000-2019, using 2010-vintage census tracts as reporting units. Population estimates are available for all unique combinations of age (18 categories), sex (two categories), and race (six categories). We provide statewide data files in this release.

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March 2023

1980 Block Boundaries, Version 3.0

March 14, 2023

NHGIS has released its third set of 1980 block boundary shapefiles and summary statistics (Version 3.0). This release adds 41 new whole or partial metropolitan areas including Detroit, Washington D.C., Dallas-Fort Worth, Houston, and Boston. A complete list of the available metropolitan areas is available here. The statewide and nationwide shapefiles have been updated to include all new metropolitan areas. A complete list of currently available metropolitan areas is provided here.

Click below for a list of the newly added metro areas:

The 1980 block summary statistics have also been expanded to include additional geographic codes and suppression flags. More documentation on the summary statistics can be found here.

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December 2022

2021 GIS Boundary Files

December 21, 2022

NHGIS has released 85 new GIS boundary files based on 2021 TIGER/Line Shapefiles. The new files correspond to the geographic units of 2021 American Community Survey data. The release includes nationwide files for 33 geographic levels and 52 state-specific files for block groups.

2017-2021 ACS 5-Year Summary File

December 13, 2022

The 2017-2021 American Community Survey (ACS) 5-Year Summary File is now available on NHGIS. Over 1,100 tables offer detailed cross-tabulations on age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

Tables are available for 87 geographic levels, down to census tracts and block groups.

NHGIS separates this summary file into four datasets, each providing tables for a different set of geographic levels:

• 2017_2021_ACS5a: 5-Year Data [2017-2021, Block Groups & Larger Areas] – 377 tables
• 2017_2021_ACS5b: 5-Year Data [2017-2021, Tracts & Larger Areas] – 696 tables
• 2017_2021_ACS5c: 5-Year Data [2017-2021, Summary by Residence 1 Year Ago] – 38 tables
• 2017_2021_ACS5d: 5-Year Data [2017-2021, Summary by Place of Work] – 34 tables

Note: NHGIS converts all special negative values to blanks.

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October 2022

Updates to Context Fields for Data Tables

October 28, 2022

A new release of NHGIS metadata and data includes wide-ranging updates to the "context fields" in NHGIS data files for summary tables. Across all NHGIS datasets, the update includes 1,428 revisions: 1,145 added fields, 60 dropped fields (which were altogether empty in our source files), and 223 fields with a revised code or description. We detail all updates in an Excel spreadsheet (link below), which lists codes and descriptions for the affected fields both before and after the update (where "<na>" indicates that the field either was not or is no longer available).

• Updates to NHGIS Context Fields, October 28, 2022

2021 ACS 1-Year Summary File

October 28, 2022

The NHGIS data collection now includes the 2021 American Community Survey (ACS) 1-Year Summary File. Over 1,300 new tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

In the 1-year dataset, tables are available only for geographic areas with populations of at least 65,000.

For information about changes from earlier ACS Summary Files, see the Census Bureau's listing of Table Changes for 2021 ACS 1-Year Estimates.

NHGIS modifies the ACS data only to replace all special negative and non-numeric values with blanks in the data columns. We do this to facilitate GIS processing.

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August 2022

1980 Block Boundaries, Version 2.0

August 19, 2022

NHGIS has released its second set of 1980 block boundary shapefiles and summary statistics (Version 2.0). This release adds 14 new metropolitan areas including New York City, Los Angeles, Baltimore, Atlanta, Memphis, and Nashville. A complete list of currently available metropolitan areas is provided here. The statewide and nationwide shapefiles and summary statistics have been updated to include all new metropolitan areas.

Click below for a list of the newly added metro areas:

Boundaries and summary statistics are available through the 1980 Block Boundaries page along with complete documentation.

New Version Number & DOI

August 19, 2022

NHGIS has updated its recommended citation to be:

Steven Manson, Jonathan Schroeder, David Van Riper, Tracy Kugler, and Steven Ruggles. IPUMS National Historical Geographic Information System: Version 17.0 [dataset]. Minneapolis, MN: IPUMS. 2022. http://doi.org/10.18128/D050.V17.0

The archival record of this version was generated from the August 1, 2022, version of the NHGIS website, data, and metadata.

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May 2022

1980 Block Boundaries, Version 1.1

May 27, 2022

NHGIS has released updated 1980 block boundary shapefiles and summary statistics (Version 1.1). This release provides additional extent selection and shapefile improvements. NHGIS now provides statewide summary statistics for all states with boundary shapefiles currently available and a smaller nationwide summary statistics CSV file containing the sixteen most requested tables from Summary Tape File 1. We also released a new nationwide shapefile to allow users to download all available metro areas in a single file. All shapefiles are now indexed on GISJOIN to speed up GIS processing.

Boundaries and summary statistics are available through the 1980 Block Boundaries page along with complete documentation.

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April 2022

2016-2020 ACS 5-Year Summary File

April 26, 2022

The 2016-2020 American Community Survey (ACS) 5-Year Summary File has been released on NHGIS. Over 1,000 tables offer detailed cross-tabulations on age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

Tables are available for 87 geographic levels, down to census tracts and block groups.

This release diverges from past NHGIS protocols in its handling of special "jam values". For earlier versions of ACS Summary Files, we replaced "." jam values with blanks in data extracts using the comma delimited (.csv) format, but we still provided the "." values in fixed-width output files. In the new release, NHGIS converts all such special values to blanks in all output formats.

The change in NHGIS protocols for special values corresponds to a change in our source files. This year, we derived the NHGIS data from a new format of ACS Summary Files. The new format uses a different set of special values--a set corresponding to the values given by the Census API rather than the values used in the original format of Summary Files. The new set uses negative numeric values almost exclusively, rather than using the "." character. To streamline our processing of the new format, we replaced all negative values with blanks. We are considering modifications to keep all the negative values and may reintroduce them in a future update.

Geographic Crosswalks for 2010-2020 ACS Data

April 1, 2022

To support comparisons between new 2020 American Community Survey (ACS) 5-year summary tables and ACS data from earlier years, NHGIS has extended its collection of geographic crosswalks to include crosswalks from 2010 block groups to 2020 block groups, census tracts, and counties, and from 2020 block groups to 2010 block groups, census tracts, and counties.

For more information, and to download the files, see the Geographic Crosswalks page.

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March 2022

1980 Block Boundaries, Version 1.0

March 8, 2022

NHGIS has released its first version of 1980 block boundary shapefiles. We derive these files primarily from the 1992 TIGER/Line files, but the 1980 block definitions in the 1992 TIGER/Line files are incomplete and often inaccurate. NHGIS therefore applied extensive manual editing, using 1980 paper block maps as a guide, to reconcile the many differences between the 1992 TIGER/Line files and the 1980 census block summary data.

The files are not yet available through the Data Finder. They are instead available through the 1980 Block Boundaries page along with complete documentation and block-level summary statistics.

This first release (Version 1.0) covers 48 metropolitan areas, listed below in order of population. We will update and extend the shapefiles in future releases as we complete block editing work for more areas.

Metro Areas Covered in Version 1.0 of NHGIS 1980 Block Boundaries

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February 2022

Time Series Tables, Release 9.0

February 23, 2022

This release extends our collection of time series tables to include data from the 2020 census (the P.L. 94-171 Redistricting Data) and from the American Community Survey 2015-2019 5-Year Summary File.

For 17 of the time series tables that are standardized to 2010 boundaries, we added 2020 data by interpolating from block-level counts in the 2020 Redistricting Data. This release extends only the standardized tables for which there are corresponding counts in the 2020 Redistricting Data, which leaves out subjects like sex, detailed age, housing tenure, and household size and relationships. We also created 2 new standardized tables to cover specific categories of age and group quarters type that are available in the 2020 Redistricting Data.

New and extended tables in Release 9.0: Standardized to 2010

These tables, like all NHGIS tables standardized to 2010, are available for 10 geographic levels: states, counties, census tracts, block groups, county subdivisions, places, congressional districts (110th-112th Congresses, 2007-2013), core based statistical areas (metropolitan and micropolitan areas), urban areas, and ZIP Code Tabulation Areas (ZCTAs).

Note: NHGIS does not yet provide time series tables standardized to 2020 boundaries.

For the nominally integrated time series tables, this release extends 95 tables: 24 now include 2020 census data and 75 now include 2015-2019 ACS data. (Two tables include both 2020 and 2015-2019 data.) As with the standardized tables, we created 2 new nominally integrated time series tables to cover specific categories of age and group quarters type that are available in the 2020 Redistricting Data.

New and extended tables in Release 9.0: Nominally integrated

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January 2022

GIS file updates: 2020 centers of population; 2010 boundaries from 2020 TIGER/Line; 2000 boundaries for Puerto Rico

January 21, 2022

An update to the NHGIS GIS files added many new files as well as updates to existing files:

• New 2020 centers of population
• 4 GIS point files depict the 2020 centers of population for states, counties, census tracts, and block groups. Complete information on the source and derivation of these points is available in the NHGIS GIS Files documentation.
• New 2010 boundaries based on 2020 TIGER/Line files
• 127 GIS boundary files, derived from the 2020 TIGER/Line Census Redistricting Data (P.L. 94-171) Shapefiles, correspond to the geographic units of 2010 census data and 2010 American Community Survey data. This includes nationwide files for 23 geographic levels and 104 state-specific files: 52 for block groups and 52 for blocks.
• Updates to 2000 boundary files based on 2010 TIGER/Line files
• Extend files to include Puerto Rico
• New files for 2000 school districts (elementary, secondary, and unified) and subminor civil divisions (Puerto Rico only)
• Revise shapefile names to use new scheme, from {[extent code]_[geog level code]10_2000} to {[extent code]_[geog level code]_2000_tl10}
• Moved GISJOIN field to first position in field ordering
• Sorted and indexed on GISJOIN
• Updated metadata
• New 2020 voting district boundaries
• Added one 2020 boundary file for voting districts, derived from the 2020 TIGER/Line Census Redistricting Data (P.L. 94-171) Shapefiles. (All other existing NHGIS 2020 boundary files were derived from the base 2020 TIGER/Line Shapefiles, which did not include voting districts.)
• Removal of "Remainder" from shapefile geographic level descriptions
• 47 shapefiles for school districts, tribal subdivisions, and voting districts had included "Remainder" in their NHGIS geographic level labels. Now they do not. (Although census and ACS summary files include data records for remainder areas for these levels, the TIGER/Line files do not include polygons for the remainder areas.)

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September 2021

Advanced Weighting in 2010-to-2020 Block Crosswalks

September 7, 2021

The NHGIS geographic crosswalks from 2010 to 2020 census blocks now include interpolation weights based on the population and housing densities of 2020 blocks, using the "target-density weighting" (TDW) model as in other NHGIS crosswalks.

The previous preliminary versions of these crosswalks, released on August 9, 2021, provided only area weights, not TDW weights, because TDW weights required data that were not yet available. We are now able to compute the TDW weights using block data from the 2020 P.L. 94-171 Redistricting Data, which were released by the U.S. Census Bureau on August 12 and added to NHGIS on August 17.

For more information, and to download the files, see the Geographic Crosswalks page.

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August 2021

Standard Block-Level Data from 2020 Census P.L. 94-171 Redistricting Data

August 25, 2021

NHGIS extended its new dataset from the 2020 Census P.L. 94-171 Redistricting Data to include tables for the standard census block geographic level: Block (by State--County--Census Tract). Except for some revisions to the geographic identifiers, the new data are identical to the original data published for summary levels 750 and 755 (State--County--Voting District/Remainder--County Subdivision--Place/Remainder--Census Tract--Block Group--Block and State--County--Voting District/Remainder--County Subdivision--Subminor Civil Division--Place/Remainder--Census Tract--Block Group--Block). We merged data from these two source levels; revised the geographic identifiers in the new data to include only state, county, tract, and block components; and associated the new data with the standard block level in NHGIS metadata. This standard level is easier to find in the NHGIS Data Finder, and the GISJOIN codes in the new data are consistent with those in the NHGIS 2020 block GIS files.

2020 GIS Boundary Files

August 19, 2021

NHGIS has released 137 new GIS boundary files based on 2020 TIGER/Line Shapefiles. The new files correspond to the geographic units of 2020 census data and 2020 American Community Survey data. The release includes nationwide files for 33 geographic levels and 104 state-specific files: 52 for block groups and 52 for blocks.

2020 Census P.L. 94-171 Redistricting Data

August 17, 2021

The 2020 P.L. 94-171 Redistricting Data Summary File has been released on NHGIS. Six tables provide data on 63 race combinations by Hispanic/Latino origin, voting age population by race and ethnicity, group quarters type, and housing occupancy/vacancy.

Tables are available for 97 geographic levels, down to block groups and blocks.

Note: With an update on August 19, 2021, we reduced the set of context fields that NHGIS delivers in 2020 redistricting data table files, hiding several low-value or unused fields.

Geographic Crosswalks Between 2010 & 2020 Census Blocks

August 9, 2021

NHGIS has extended its collection of geographic crosswalks to include "forward" crosswalks from 2010 to 2020 census blocks and "backward" crosswalks from 2020 to 2010 census blocks.

The forward crosswalks are preliminary versions because the allocation weights in NHGIS crosswalks require data from the "target year" that are not yet available. E.g., for a 2010 block that corresponds to two 2020 blocks, NHGIS will base the final allocation weights on the 2020 densities of population and housing in the two target blocks. Because the 2020 block data have not yet been released, the preliminary forward crosswalk provides only area weights, indicating the proportion of each 2010 block's area lying in each 2020 block.

The weights in the backward 2020-2010 crosswalks are based on already-available 2010 block data, so they are now complete.

For more information, and to download the files, see the Geographic Crosswalks page.

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June 2021

New Version Number & DOI

We have updated the version number and DOI for NHGIS, and the recommended citation is now:

Steven Manson, Jonathan Schroeder, David Van Riper, Tracy Kugler, and Steven Ruggles. IPUMS National Historical Geographic Information System: Version 16.0 [dataset]. Minneapolis, MN: IPUMS. 2021. http://doi.org/10.18128/D050.V16.0

We have preserved an archival record for version 16 generated from the June 22, 2021, version of the NHGIS website, data, and metadata.

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January 2021

2015-2019 ACS 5-Year Summary File & 2019 GIS Boundary Files

January 13, 2021

2015-2019 ACS 5-Year Summary File

The 2015-2019 American Community Survey (ACS) 5-Year Summary File has been released on NHGIS. Over 1,000 tables offer detailed cross-tabulations on age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

Tables are available for 87 geographic levels, down to census tracts and block groups.

In order to facilitate GIS processing of the data, NHGIS replaces "." jam values with blanks for files in the comma delimited (.csv) output format. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2019 ACS technical documentation.

2019 GIS Boundary Files

NHGIS has released 85 new GIS boundary files based on 2019 TIGER/Line Shapefiles. The new files correspond to the geographic units of the 2019 American Community Survey 1-Year and 5-Year datasets. The release includes nationwide files for 33 geographic levels as well as 52 state-specific files for block groups.

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October 2020

2019 ACS 1-Year Summary File

October 21, 2020

The 2019 American Community Survey (ACS) 1-Year Summary File has been released on NHGIS. Over 1,300 tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

In the 1-year dataset, tables are available only for geographic areas with populations of at least 65,000.

For information about changes from 2018 ACS Summary Files, see the Census Bureau's listing of 2019 Table & Geography Changes.

NHGIS modifies the ACS data only to replace "." jam values with blanks for files in the comma delimited (.csv) output format. We do this to facilitate GIS processing. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data requests. Additional information on jam values can be found within the ACS technical documentation.

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September 2020

New Version Number & DOI

September 11, 2020

NHGIS has updated its recommended citation to be:

Steven Manson, Jonathan Schroeder, David Van Riper, Tracy Kugler, and Steven Ruggles. IPUMS National Historical Geographic Information System: Version 15.0 [dataset]. Minneapolis, MN: IPUMS. 2020. http://doi.org/10.18128/D050.V15.0

The archival record of this version was generated from the August 1, 2020, version of the NHGIS website, data, and metadata.

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August 2020

Geographic Crosswalks from 1990 and 2000 Block Group Parts and for Individual States

August 21, 2020

NHGIS has extended its collection of geographic crosswalks to include crosswalks from 1990 and 2000 block group parts (BGPs), the smallest units for which the Census Bureau published summary tables covering "long-form subjects" (e.g., income, education, employment, migration, commuting, etc.). Separate crosswalk files identify relationships from source BGPs to target 2010 block groups, census tracts, and counties. The BGP crosswalks include four interpolation weights, indicating the expected proportions of each source zone's population, families, households, and housing units located in each target zone.

We have also published both nationwide and state-specific files for each type of crosswalk. The new state-specific files are available not only for the new BGP crosswalks but for the previously available block-to-block crosswalks.

For more information, and to download the files, see the Geographic Crosswalks page.

Updates to "Block Group Part" Geographic Levels

August 12, 2020

A new release of NHGIS metadata and data includes several improvements and corrections to "Block Group Part" (BGP) geographic levels (compound levels that represent the spatial intersections between block groups and other non-nesting levels):

• Corrections
• The two BGP levels used in 1990 (blck_grp_595 and blck_grp_598) had included the incorrect Congressional District (CD) level in their hierarchies. Instead of using the 103rd CDs (as used by most other 1990 compound levels), these levels now correctly use the 100th-102nd CDs. This change added the codes for the 100th-102nd CDs into the GISJOIN identifiers for these BGPs, which eliminated many duplicate GISJOIN identifiers.
• A 1990 STF1 record for level blck_grp_598 in Providence, Rhode Island, (GISJOIN="G44000705900059000012402029999999648012") had contained invalid data for two tables (NH9. Tenure by Race of Householder, NH10. Hispanic Origin of Householder by Race of Householder). The values are now all correctly set to zero.
• Improvements
• The standard, finest-resolution BGPs for 1990, 2000, and 2010 datasets (blck_grp_598 and blck_grp_090) have been added to the "Most Popular" group of geographic levels, the default group shown when the Geographic Levels filter pop-up is opened in the NHGIS Data Finder. The initial view of this pop-up hides compound levels, but if a user clicks on "Show Compound Geographic Levels," these two levels will now appear.
• The labels of all BGP levels have been revised to include, in square brackets, a brief description of the years and/or datasets in which the BGP level is used, making it easier for users to find and select the appropriate BGP level(s).
• The NHGIS IDs for three BGP levels have been simplified by deleting suffixes that indicated the CD levels used in the BGP hierarchies: blck_grp_584_91, blck_grp_595_103, and blck_grp_598_103 are now blck_grp_584, blck_grp_595, and blck_grp_598.

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April 2020

2018 GIS Boundary Files

April 2, 2020

NHGIS has released 85 new GIS boundary files based on 2018 TIGER/Line Shapefiles. The new files correspond to the geographic units of the 2018 American Community Survey 1-Year and 5-Year datasets. The release includes nationwide files for 33 geographic levels as well as 52 state-specific files for block groups.

This release includes several improvements from previous versions of NHGIS shapefiles:

• All features are sorted by GISJOIN in each shapefile
• The GISJOIN field is in the first column position (after the feature ID and geometry) in all shapefile attribute tables
• The GISJOIN field is indexed in all shapefiles, which will make joins based on GISJOIN run more efficiently in several software environments
• The shapefile metadata include several revisions and improvements, including current citation and use requirements

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January 2020

1790 Data Corrections

January 28, 2020

A new release of NHGIS data includes several corrections for tables in the 1790 Census dataset (1790_cPop):

• Table NT18 (Total Number of Slaves) was missing counts for 6 states (DE, GA, MA, NJ, VT, VA) and their counties. We filled in the missing values using counts for "Non-White: Slave" from NT6 (Race/Slave Status).
• NHGIS counts for Massachusetts and Virginia generally represent their whole 1790 extents, which combine the separate modern extents of Massachusetts with Maine and Virginia with Kentucky, but there were a few exceptions where NHGIS counts did not include the Maine and Kentucky populations. This was true for the White and Black/Nonwhite counts for both states (in tables NT6 and NT21) and for "All other nationalities" for Massachusetts (in table NT12). Also, the summed Virginia + Kentucky counts were off by one digit in two cases: in NT4, the Virginia count of males 16 years and over was 116,090 but should be 126,090, and in NT6, the count of non-white slaves was 305,067 but should be 305,057. The new release corrects all of these errors.

2014-2018 ACS 5-Year Summary File

January 28, 2020

The 2014-2018 American Community Survey (ACS) 5-Year Summary File has been released on NHGIS. Over 1,000 tables offer detailed cross-tabulations on age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

Tables are available for 87 geographic levels, down to census tracts and block groups.

In order to facilitate GIS processing of the data, NHGIS replaces "." jam values with blanks for files in the comma delimited (.csv) output format. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2018 ACS technical documentation.

Label Corrections in 2000 SF3 Datasets: Replace "Unemployed" with "Not Employed"

January 28, 2020

The original 2000 Summary File 3 includes several disability-status-by-employment-status tables where "Not employed" refers to all civilian persons who were either unemployed or not in labor force. NHGIS had previously identified all of these instances as "Unemployed" in both the variable and category labels.

There were 10 problem tables in NHGIS dataset 2000_SF3a: NP042E, NPCT027B, NPCT028B, NPCT029B, NPCT030B, NPCT031E, NPCT032E, NPCT068E, NPCT068J, NPCT068P.

Table NP042E also appears in dataset 2000_SF3b and had the same problem.

We have corrected the variable labels and category assignments for all of these tables.

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October 2019

2018 ACS 1-Year Summary File

October 23, 2019

The 2018 American Community Survey (ACS) 1-Year Summary File has been released on NHGIS. Over 1,300 tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

In the 1-year dataset, tables are available only for geographic areas with populations of at least 65,000.

NHGIS modifies the ACS data only to replace "." jam values with blanks for files in the comma delimited (.csv) output format. This was done to facilitate GIS processing. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data requests. Additional information on jam values can be found within the 2018 ACS technical documentation.

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September 2019

New Version Number & DOI

September 6, 2019

NHGIS has updated its recommended citation to be:

Steven Manson, Jonathan Schroeder, David Van Riper, and Steven Ruggles. IPUMS National Historical Geographic Information System: Version 14.0 [Database]. Minneapolis, MN: IPUMS. 2019. http://doi.org/10.18128/D050.V14.0

Improved Queuing of Data Extract Requests

September 3, 2019

NHGIS has implemented three changes to its data extract queuing protocols that will improve system efficiency and stability:

1. NHGIS now computes a "size index" for all requests based on the combination of tables, geographic levels, years, breakdowns, and GIS files selected. This index has a strong correlation with extract processing time. Requests with larger size indices are handled by a smaller number of extract processors, ensuring that smaller requests will generally not be "blocked" by long-running requests.
2. Requests with extremely large size indices--those expected to surpass an 8-hour processing time--are now prohibited. A user who submits such a request will be instructed to split it up into smaller requests.
3. While the NHGIS system is processing a request by a given user, the queuing protocols will assign any subsequent request from the same user a somewhat lower priority than its size index would warrant, ensuring that no single user can monopolize all extract processors.

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July 2019

Metadata Corrections

July 1, 2019

A new release of NHGIS metadata includes corrections to several variable labels in dataset 2000_SF3a (2000 Census: SF 3a - Sample-Based Data [Areas Larger Than Block Groups]).

In tables NPCT046A, NPCT073B, NPCT073E, and NPCT073H, each variable that had included "No earnings" in its label actually supplied counts for "With earnings" and vice versa.

All of the affected variables are now correctly labeled.

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June 2019

County-Level Marriage & Divorce Counts: 1867-2010

June 11, 2019

NHGIS has added a new dataset (1867_2010_cMD) that provides counts of marriages and divorces by county for a selection of 70 years between 1867 and 2010.

Specifically, the dataset includes counts for 1867-1886, 1890, 1900, 1916, 1922-1932, 1949-1950, 1952, 1957-1987, 2000, and 2010. No marriage counts are available for 1890 or 1900, and no divorce counts are available for 1949.

We thank our partners at the National Center for Family and Marriage Research (NCFMR) at Bowling Green State University for compiling and sharing this resource. NCFMR researchers derived the 2000 and 2010 data from county court record information obtained through individual state or county agencies. They derived the earlier data from print reports from the U.S. Bureau of Labor (1867-1886), the U.S. Census Bureau (1890, 1900, 1916, 1922-1932), the National Office of Vital Statistics (1949-1950, 1952, 1957-1958), and the National Center for Health Statistics (1959-1987). NHGIS researchers reformatted the data and enriched the metadata for redistribution.

We also thank the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) for funding this work.

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January 2019

2000 and 2010 Centers of Population for States, Counties, Tracts, and Block Groups

January 23, 2019

NHGIS has released GIS point files depicting the 2000 and 2010 centers of population for states, counties, census tracts, and block groups.

Complete information on the source and derivation of these points is available in the NHGIS GIS Files documentation.

2017 GIS Boundary Files

January 23, 2019

NHGIS has released 85 new GIS boundary files based on 2017 TIGER/Line Shapefiles. The new files correspond to the geographic units of the 2017 American Community Survey 1-Year and 5-Year datasets. The release includes nationwide files for 33 geographic levels as well as 52 state-specific files for block groups.

2013-2017 ACS 5-Year Summary File

January 17, 2019

The 2013-2017 American Community Survey (ACS) 5-Year Summary File has been released on NHGIS. Over 1,000 tables offer detailed cross-tabulations on age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

Tables are available for 87 geographic levels, down to census tracts and block groups.

In order to facilitate GIS processing of the data, NHGIS replaces "." jam values with blanks for files in the comma delimited (.csv) output format. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2017 ACS technical documentation.

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November 2018

2017 ACS 1-Year Summary File

November 14, 2018

The 2017 American Community Survey (ACS) 1-Year Summary File has been released on NHGIS. Over 1,300 tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

In the 1-year dataset, tables are available only for geographic areas with populations of at least 65,000 persons.

NHGIS modifies the ACS data only to replace "." jam values with blanks for files in the comma delimited (.csv) output format. This was done to facilitate GIS processing. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2017 ACS technical documentation.

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September 2018

New Version Number & DOI

We have updated the version number and DOI for NHGIS, and the recommended citation is now:

Steven Manson, Jonathan Schroeder, David Van Riper, and Steven Ruggles. National Historical Geographic Information System: Version 13.0 [dataset]. Minneapolis, MN: IPUMS, 2018. https://doi.org/10.18128/D050.V13.0

We have preserved an archival record for version 16 generated from the September 6, 2018, version of the NHGIS website, data, and metadata.

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August 2018

Upgrade for Processing Nominally Integrated Time Series

August 14, 2018

With the release of Version 2.5 of its extract engine, NHGIS now employs an Apache Spark cluster-computing framework to process extracts of nominally integrated time series, achieving major reductions in processing time for time-series requests. Our test extracts of nominally integrated time series run 5-20 times faster with the new system.

To support the new system, NHGIS now maintains internally complete data files for all of its nominally integrated time series in Apache Parquet format. Previously, the extract engine would only generate nominally integrated data from internal fixed-width ASCII source data files on-demand.

This upgrade affects only the processing of nominally integrated time series tables. We implemented a similar upgrade for the processing of source tables with Version 2.0 of the extract engine, released in October 2017, and for geographically standardized time series with Version 2.4, released in March 2018. The new release, Version 2.5, completes the transition of the NHGIS extract system from serial processing of ASCII fixed-width source files to parallel processing of Parquet source files.

Corrections in 2016 State, Division, & Region Shapefiles

August 14, 2018

In the original version of our 2016 State, Division, and Region shapefiles, the state of Florida, and the division and region that include Florida, were subdivided into multiple polygons. These areas are now properly represented by a single polygon in each file.

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July 2018

Label Correction for 1970 County Subdivision

July 18, 2018

A new release of NHGIS metadata has corrected the label of a county subdivision in Nuckolls County, Nebraska, in dataset 1970_Cnt1. The label was "Hignland precinct" and is now "Highland precinct".

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April 2018

Vital Statistics: 1970-2007

April 2, 2018

NHGIS has added a new dataset (1970_2007_cVS) summarizing annual births and deaths for counties, states, and the nation, for 1970, 1975, 1980, 1985, and annually from 1990-2007. The data are derived from the USA Counties database of the U.S. Census Bureau, which includes birth and death data from the National Center for Health Statistics (NCHS) and population estimates from the U.S. Census Bureau Population Estimates program. NHGIS researchers organized the data into tables and assigned metadata on topics, categories, etc.

This is the third planned release of vital statistics datasets, filling out NHGIS's collection of state and county birth and death counts for most years from 1915 through 2007.

Adjustment to 1980 Data on Aggregate Value and Price Asked

April 2, 2018

For the following tables, NHGIS now supplies data values in actual dollar amounts rather than as multipliers of $250 (as in the original source data):

• 1980_STF2a, NTA31: Aggregate Value [Specified Owner-Occupied Noncondominium Housing Units with Complete Plumbing Facilities for Exclusive Use]
• 1980_STF2a, NTA43: Aggregate Price Asked by Condominium Status [Specified Vacant-for-Sale Only Housing Units]
• 1980_STF2b, NTB39: Aggregate Value by Condominium Status [Specified Owner-Occupied Noncondominium Housing Units and Owner-Occupied Condominium Housing Units]
• 1980_STF3, NT140: Aggregate Value [Specified Owner Occupied Noncondominium Housing Units]
• 1980_STF4Ha, NTHA25: Aggregate Price Asked by Condominium Status [Specified Vacant-for-Sale Only Noncondominium Housing Units and Vacant-for-Sale-Only Condominium Housing Units]
• 1980_STF4Hb, NTHB19: Aggregate Value by Condominium Status [Specified Owner-Occupied Noncondominium Housing Units and Owner-Occupied Condominium Housing Units]
• 1980_STF4Hb, NTHB80: Aggregate Value by Age of Householder and Spouse [Specified Owner-Occupied Noncondominium Housing Units with Householder or Spouse 60 Years and Over]

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March 2018

Upgrade for Processing Standardized Time Series

March 26, 2018

With the release of Version 2.4 of its extract engine, NHGIS now employs an Apache Spark cluster-computing framework to process extracts of geographically standardized time series, achieving major reductions in processing time for large time-series requests. For example, to build extracts of standardized time series of block group data including several large tables, our tests run about 3 times faster with the new system.

To support the new system, internal NHGIS data files are now stored in Apache Parquet format.

This upgrade affects only the processing of standardized time series tables--not nominally integrated time series tables or GIS files. We implemented a similar upgrade for the processing of source tables with Version 2.0 of the extract engine, released in October 2017. We plan to implement Spark-based processing of nominally integrated time series tables soon.

Data Corrections

March 14, 2018

With a new release of data and metadata, coupled with an extract engine update (Version 2.3), NHGIS has corrected three problems with data file content that arose with the release of Version 2.0 of the extract engine in October 2017:

• If a user requested multiple breakdowns (e.g., multiple industry codes in County Business Patterns data) in a "combined" layout (putting all data for a single year in one file), and a geographic unit had data for some of the requested breakdowns but not for others, then our system mishandled the entries for the "missing" data, failing to insert an adequate number of blank entries, resulting in the misalignment of all remaining data values in the data record.
• For the following combinations of dataset, year, and geographic level, a subset of the names of geographic units were blank, and for requests in fixed-width format, the extract engine erroneously collapsed the empty columns in the "blank geography name" rows, resulting in the misalignment of subsequent columns:
• 1970_1971_CBP, 1970 and 1971, county
• 1972_1973_CBP, 1972, county
• 1974_1987_CBPa, 1980, county
• 1988_1997_CBPa, 1990, county
• 1990_SSTF17, 1990, msa_cmsa
• 1998_2002_CBPa, 2000, county
• In County Business Patterns data for non-decennial years, columns for the names of geographic units (states, counties, etc.) were generally blank.

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February 2018

Vital Statistics: 1939-1972

February 6, 2018

NHGIS has added two new datasets (1939_1959_cVS and 1959_1972_cVS) summarizing annual births and deaths for counties, states (including territories), and the nation, 1939-1972. The 1939-1967 data are derived from annual reports of vital statistics from the U.S. Census Bureau (1939-1944) and the U.S. Public Health Service (1945-1967). The 1968-1972 data are derived from individual-level microdata (either birth certificates or the Compressed Mortality File) from the National Center for Health Statistics. Michael Haines at Colgate University provided NHGIS with digital source data, and NHGIS researchers organized the data into tables and assigned metadata on topics, categories, etc.

This is the second release in a planned series that will extend NHGIS's collection to include state and county birth and death counts for most years from 1915 through 2007.

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January 2018

Option to Select/Deselect All Years in a Dataset

January 17, 2018

Through the Options page of the NHGIS Data Finder, users now have the ability to select or deselect all years in a multi-year dataset with a single click.

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December 2017

2012-2016 ACS 5-Year Summary File

December 21, 2017

The 2012-2016 American Community Survey (ACS) 5-Year Summary File has been released on NHGIS. Over 1,000 tables offer detailed cross-tabulations on age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

Tables are available for 87 geographic levels, down to census tracts and block groups.

In order to facilitate GIS processing of the data, NHGIS replaces "." jam values with blanks for files in the comma delimited (.csv) output format. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2016 ACS technical documentation.

2016 GIS Boundary Files

December 21, 2017

NHGIS has released 85 new GIS boundary files based on 2016 TIGER/Line Shapefiles. The new files correspond to the geographic units of the 2016 American Community Survey 1-Year and 5-Year datasets. The release includes nationwide files for 33 geographic levels as well as 52 state-specific files for block groups.

Vital Statistics: 1915-1941

December 21, 2017

NHGIS has added a new dataset (code 1915_1941_cVS) summarizing annual births and deaths from 1915 through 1941. The data are derived from the Census Bureau's vital statistics annual reports for states (including territories) and counties. The geographic extent of coverage is limited to the Birth and Death Registration Areas established in each year. Michael Haines at Colgate University provided NHGIS with digital source data, which were entered from printed census publications, and NHGIS researchers organized the data into tables and assigned metadata on topics, categories, etc. The new dataset includes 21 variables organized into 14 tables.

This is the first release in a planned series that will extend NHGIS's collection to include state and county birth and death counts for most years through 2007.

Time Series Tables, Release 8.1

December 4, 2017

With Release 8.1, NHGIS has dropped Puerto Rico records from its geographically standardized time series tables. The NHGIS database does not include Puerto Rico data for 2000 or earlier years, so the Puerto Rico records in standardized tables had previously contained valid counts only for 2010. Cells for 2000 and 1990 had been blank.

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November 2017

2016 ACS 1-Year Summary File

November 30, 2017

The 2016 American Community Survey (ACS) 1-Year Summary File has been released on NHGIS. Over 1,300 tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

In the 1-year dataset, tables are available only for geographic areas with populations exceeding 65,000 persons.

Users should be aware that NHGIS has modified ACS data to replace "." jam values with blanks for files in the comma delimited (.csv) output format. This was done to facilitate GIS processing. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2016 ACS technical documentation.

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October 2017

NHGIS Extract Engine, Version 2.0: Major Upgrade for Processing Source Table Requests

October 17, 2017

With the release of Version 2.0 of its extract engine, NHGIS now employs an Apache Spark cluster-computing framework to process extracts of source tables, achieving major reductions in processing time for large data requests. For example, to build extracts of census block data tables with millions of records and dozens of columns, our tests run 5 to 30 times faster with the new system, in some cases reducing processing time from a few hours to a few minutes.

To support the new system, internal NHGIS data files are now stored in Apache Parquet format.

This upgrade affects only the processing of source tables--not time series tables or GIS files--and some types of requests (especially those involving large numbers of datasets, geographic levels, and/or breakdowns) may still require a long time to complete. We plan to implement Spark-based processing of time series tables soon.

Environmental Summaries for Counties and Census Tracts

October 13, 2017

NHGIS has released its first set of environmental summaries. Users may download land cover summaries for 2015 counties and 2000, 2010, and 2015 census tracts, or climate summaries for counties.

The land cover data come from the National Land Cover Database (NLCD), which is derived from 30-meter resolution Landsat imagery. The NLCD summaries identify the area and proportion of area covered by each of 16 land cover classes in 2001, 2006, and 2011.

The climate data summarize precipitation and minimum, maximum, and mean temperatures from the PRISM Climate Group. The climate summaries are available for monthly and annual time steps from 1895-2014 and for 30-year normals covering the 1981-2010 time period.

NHGIS land cover summaries are available in three file layouts: time varies by column, time varies by row, and time varies by file. Climate summaries are available in the time varies by row layout.

For more information, or to download the files, see the new Environmental Summaries resource page.

1900-2015 Place Points

October 12, 2017

NHGIS has released GIS point files depicting the locations of incorporated, unincorporated, and census-designated places from 1900 to 2015.

The new files identify the places that are listed in the U.S. Census Bureau's published tables for each decennial census between 1900 and 2010 and for each American Community Survey release between 2009 and 2015.

To find the place point files in the Data Finder, first apply a "Place" Geographic Levels filter or a Years filter for one of the covered years and then look under the GIS BOUNDARY FILES tab for GIS files with a geographic level of "Place (Points)". (Files with a geographic level identified only as "Place" contain boundary polygons, not points.)

For detailed information on the derivation and content of NHGIS place point files, see the Point Files documentation page.

Final Urban/Rural Counts for Tracts, Block Groups & Blocks in 2000 SF1 Datasets

October 5, 2017

In NHGIS datasets 2000_SF1a (2000 Census: SF 1a - 100% Data [Areas Larger Than Block Groups]) and 2000_SF1b (2000 Census: SF 1b - 100% Data [Blocks & Block Groups]), the following four tables now contain final counts for census tracts, block groups, and census block geographic levels:

• NP002A. Population by Urban and Rural
• NP002B. Urban Population by Type of Urban Area
• NH002A. Housing Units by Urban and Rural
• NH002B. Urban Housing Units by Type of Urban Area

Counts for these two compound geographic levels are now also final counts:

• tract_080: State--County--County Subdivision--Place/Remainder--Census Tract
• blck_grp_091: State--County--County Subdivision--Place/Remainder--Census Tract--Block Group

Previously, the counts in these tables were final for most other levels, but the urban and rural counts for the tract, block group, and block levels were all zeros, with all population and housing units counted as "Not defined for this file". NHGIS supplied the final counts for these levels only in the separate dataset 2000_SF1S (2000 Census: SF 1S - Urban/Rural Counts [Blocks, Block Group Parts & Tract Parts]).

Now, the counts from the supplemental "S" dataset have been transferred into the core NHGIS SF1 datasets.

Time Series Tables, Release 8.0

October 5, 2017

This release extends our collection of time series tables with several significant advancements:

Standardized 1990 data:

NHGIS has extended its geographically standardized time series tables to include 1990 data for 2010 census units.

The standardized 1990 data, like our existing standardized 2000 data, are derived entirely from census block data, ensuring a generally high level of accuracy. The topics covered by the tables are limited to those for which 1990 block data are available. This excludes subjects covered only in the 1990 census long-form questionnaire (e.g., income, poverty, education, marital status, place of birth, etc.).

Subtraction:

This release is the first to utilize subtraction for the computation of comparable statistics across time, which has enabled the construction of several new tables and the extension of several existing tables, including both nominally integrated and geographically standardized tables, to cover more categories, years, and/or geographic levels.

Simplified single race/ethnicity tables:

Three new "Single Race/Ethnicity" tables use a simplified scheme of integrated race/ethnicity categories, which groups all persons of Hispanic or Latino origin into a single category and, for years since 2000, allocates all persons of Two or More Races and not Hispanic or Latino into one of the single-race categories from prior censuses, enabling more direct comparisons of race data across the 1990-2000 period.

The allocation of race categories is based on the approach used by IPUMS USA to allocate single-race categories to multiple-race individuals for the "RACESING" microdata variable. In that case, "Each multiple-race person is assigned to the single race response category deemed most likely [if the person had been asked to choose a single race, as in the 1990 census], depending on the individual's age, sex, Hispanic origin, region and urbanization level of residence, and the racial diversity of their local area."

It is not possible to directly apply the RACESING approach to census summary tables for NHGIS time series. Instead, for each of the 63 possible combinations of the 6 main race categories in 2000 and 2010, we assign to all persons who reported a combination, nationwide, the single race category corresponding to the most common (plurality) RACESING category for such persons in the IPUMS-USA 2000 5-percent sample of U.S. population. The NHGIS single-race category-assignment table (Excel format) lists all of the 63 assignments along with a summary of RACESING counts for each multiple-race combination.

Housing counts by ethnicity, race, and tenure:

The release includes 9 new standardized tables and 10 new nominally integrated tables providing counts of occupied housing units by race and Hispanic or Latino origin of the householder, in total and by tenure.

Summary of new, extended, and revised time series tables in Release 8.0   
(Ext./Rev. = extended or revised, Stdzd. = standardized to 2010, Nom. Integ. = nominally integrated)

Deprecated table

With Release 8.0, one time series table (A78. Persons Excluding Those of Some Other Race by Sex [2] by Race [5*]) has been removed from the NHGIS collection. With the implementation of subtraction, we are now able to provide all content from the removed table through two others: B21. Persons by Sex [2] by Race [5*] and AX3. Persons by Sex [2] by Race [6*].

Revisions to nominally integrated time series tables for Release 8.0

Data & Metadata Corrections

October 5, 2017

A new release of NHGIS data and metadata corrects several issues in NHGIS tables, listed here by dataset:

• 1970_Cnt4H - 1970 Census: Count 4H - Sample-Based Housing Data
• A series of data columns providing counts of housing units and persons by tenure and number of persons in unit, beginning in Table NT37G and continuing into NT37L, had been jumbled. NHGIS metadata has been revised so that all variables in these tables now provide the correct data.
• 1980_STF3 - 1980 Census: STF 3 - Sample-Based Data
• The original 1980 STF3 Table 14 provides 5 counts for persons of Spanish origin--first, the total of all such persons, and then, that group broken down by race (4 categories). NHGIS processing separated the total from the 4 race counts in two data tables. The total was placed into NHGIS Table NT14B following the race counts in NT14A. The actual order of the columns in our internal data file, however, still followed the source order, with the universe total coming first. All the race variables in NT14A supplied adjacent values, and the universe total in NT14B supplied the count for the "Other" race. All values are now correctly labeled.
• 2000_SF1a and 2000_SF1b - 2000 Census: SF1a - 100% Data [Areas Larger Than Block Groups] and SF1b - 100% Data [Blocks & Block Groups]
• In tables NP037C and NP038D, some errors in the spelling of "Institutionalized" and "Noninstitutionalized" have been corrected.

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August 2017

Geographic Crosswalks from 1990 and 2000 Blocks to 2010 Blocks

NHGIS now provides geographic crosswalk files to support the allocation of summary data from one census year to another. At this time, NHGIS provides crosswalks for two settings: 2000 blocks to 2010 blocks and 1990 blocks to 2010 blocks. We plan to add more crosswalks in future releases.

The interpolation weights given in the crosswalks are the same weights that NHGIS uses to produce geographically standardized time series tables.

For more information, or to download the files, see the new Geographic Crosswalks resource page.

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July 2017

New Version Number & DOI

As of July 25, 2017, NHGIS has updated its recommended citation to be:

Steven Manson, Jonathan Schroeder, David Van Riper, and Steven Ruggles. IPUMS National Historical Geographic Information System: Version 12.0 [Database]. Minneapolis: University of Minnesota. 2017. http://doi.org/10.18128/D050.V12.0

Data & Metadata Corrections

A new release of NHGIS data and metadata corrects several issues in NHGIS source tables and boundary data, listed here by dataset:

• 1970_Cnt3 - 1970 Census: Count 3 - 100% Data [Blocks & Tracts: Restricted to Areas with Block Statistics]
• One census block record (GISJOIN "G39015107138114", Ohio, Stark County) contained some incorrect values in some fields in tables NT34B - NT38
• 1970_1971_CBP - 1970-1973 County Business Patterns (1967 SIC Codes): Business Data 1970-1971 [States & Counties]
• In 1970 state-level data:
• Some numeric fields contained a "D" value indicating suppressed values. Following our practice for other County Business Patterns datasets, we have moved the D's into a separate column in NHGIS's internal files and replaced them with zero values. NHGIS currently omits the suppression flag columns from output data extracts. We plan to modify extract protocols to include the suppression flags in a future system update.
• Data for SIC Code 2652 (Manufacturing--Paper and Allied Products--Paperboard Containers and Boxes--Set-Up Paperboard Boxes) included two records for Maryland, one of which provided values for South Carolina.
• In data for SIC Code 2653 (Manufacturing--Paper and Allied Products--Paperboard Containers and Boxes--Corrugated and Solid Fiber Boxes), the South Carolina value for NT001. Total Mid-March Employees contained an erroneous non-numeric character. It is now correctly given as 791.
• In 1971 county-level data:
• The area name for Cordova-McCarthy, Alaska, had erroneously been given as "Haines", which is a separate Alaska county equivalent listed on a separate line.
• 1972_1973_CBP - 1970-1973 County Business Patterns (1967 SIC Codes): Business Data 1972-1973 [States & Counties]
• As noted above for 1971, the 1972 and 1973 area name for Cordova-McCarthy, Alaska, had erroneously been given as "Haines", which is a separate Alaska county equivalent listed on a separate line.
• 1974_1987_CBPb - 1974-1987 County Business Patterns (1972 SIC Codes): Business Data [US & States]
• In state-level data for SIC's 3900 (Manufacturing--Miscellaneous Manufacturing Industries) and 399\ (Manufacturing--Administrative and Auxiliary), there had been two records for Nevada
• In state-level data for SIC's 5900 (Retail Trade--Miscellaneous Retail) and 599\ (Retail Trade--Administrative and Auxiliary), there had been two records for New Mexico
• 1990_STF1 - 1990 Census: STF 1 - 100% Data
• Four census block records contained some bad values (miscellaneous characters or blanks) in some fields:

• 1994_1997_CBP - 1988-1997 County Business Patterns (1987 SIC Codes): Business Data 1994-1997 [ZIP Code Areas]
• 1996 data for industry 99-- (UNCLASSIFIED ESTABLISHMENTS) included two records for most ZIP Codes
• 1998_2002_CBPa - 1998-2002 County Business Patterns (1997 NAIC Codes): Business Data [Counties]
• Data for six industries in the 62---- (Health care and social assistance) group had included two records for Dale, Alabama
• 1998_2002_CBPc - 1998-2002 County Business Patterns (1997 NAIC Codes): Business Data [ZIP Code Areas]
• Data for industries 95---- (Auxiliaries (exc corporate, subsidiary and regional mgt)) and 99---- (Unclassified establishments) included two records for most ZIP Codes
• 2015 GIS boundary data
• For shapefiles with a nationwide extent, we adjusted the case of "us" in the shapefile names to "US"
• We removed polygons representing the U.S. Virgin Islands, Guam, and the Northern Marianas Island from four shapefiles (counties, congressional districts, urban areas, and ZIP Code Tabulation Areas)

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May 2017

Data & Metadata Corrections

A new release of NHGIS data and metadata corrects several issues in NHGIS source tables, listed here by dataset:

• 1940_tPH_Major - 1940 Census: Population & Housing Data [Tracts & NY Health Areas: Major Cities & Surrounds]
• In table NT3 (Native Born White Population) the data value for census tract G25001700001, Middlesex County, Massachusetts, had been 3229. We have corrected it to be 2229, matching the value in the original print census volume.
• In table NT9 (White Population by Nativity by Sex) the "Foreign >> Male" data value for census tract G26016300571, Wayne County, Michigan, had been "163 2160". We have deleted the erroneous "163" component, leaving a correct value of 2160.
• 1970_Cnt1 - 1970 Census: Count 1 - 100% Data [Block Groups, Enum. Districts, Cong. Districts, etc.]
• The dataset had included a duplicate, partial record for Congressional District 7 in Washington. We have deleted the problem record, leaving a single, complete record for this district.
• 1980_STF1 - 1980 Census: STF 1 - 100% Data and STF 3 - Sample-Based Data
• Two geographic levels (cty_sub_02898 and cty_sub_511_098) use an idiosyncratic coding scheme in the original 1980 summary tape files, whereby minor civil divisions are distinguished by a "MCDSEQNO" sequence number that is unique within each state, unlike standard county subdivision codes, which are unique within each county. NHGIS output files had previously omitted the MCDSEQNO column. Output files now include the column, and the labels of these levels have been revised to indicate that they are limited to county subdivisions with at least 10,000 residents in MCD states.
• 1980_STF2a - 1980 Census: STF 2a - 100% Detailed Data
• In table NTA15B (Tenure by Persons in Unit and Household Type by Age of Householder) for the tract_02498 geographic level (Census Tract/Block Numbering Area by State--Standard Metropolitan Statistical Area--County--Place), the data value for the 149th variable ("Renter-occupied >> 2 or more persons: Nonfamily household: Female householder >> Householder 35 to 44 years") for tract part G3907960023041000015, Clark County, Ohio, had been "\02". We have deleted the erroneous "\" character, leaving a correct value of 2.
• 2000_SF3a - 2000 Census: SF 3a - Sample-Based Data [Areas Larger Than Block Groups]
• Numerous data columns in tables NPCT036A-NPCT061C and NH028A ff. were misaligned, resulting in erroneous data values, for two records at two geographic levels:
• G230028050 - Aroostook Band of Micmac TDSA, ME - level res_only_551_109: American Indian Reservation [excluding trust lands] by State--Congressional District (2005-2007, 109th Congress)
• G32002051099999 - Carson Colony, NV - level trbl_sub_554_108: Tribal Subdivision/Remainder by State--Congressional District (2003-2005, 108th Congress)--American Indian Area/Alaska Native Area/Hawaiian Home Land

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April 2017

Data & Metadata Corrections

A new release of NHGIS data and metadata corrects several issues in NHGIS source tables:

• The following data files contained duplicate/extraneous rows that have now been removed:
• 1974_1987_CBPb - 1974-1987 County Business Patterns (1972 SIC Codes): Business Data [US & States]
• State data for Tennessee, industry breakdowns for ---- Total; 40-- Transportation and Other Public Utilities; 4200 Trucking and Warehousing; and 4210 Trucking, Local and Long Distance
• 2000_SF2 - 2000 Census: SF 2 - 100% Data with Race/Ethnicity Breakdown
• Tract data for Wyoming, breakdowns for 5 races, alone or in combination, not Hispanic or Latino
• 2010_SF1a - 2010 Census: SF 1a - P & H Tables [Blocks & Larger Areas]
• Data for the place_172 geographic level (State--Consolidated City--Place within Consolidated City)
• 2010_SF1b - 2010 Census: SF 1b - PCT & HCT Tables [Tracts & Larger Areas]
• Data for the place_172 geographic level (State--Consolidated City--Place within Consolidated City)
• 2010_SF2a - 2010 Census: SF 2a - PCT & HCT Tables [Tracts & Larger Areas]
• Data for 3 geographic levels: county_155 (State--Place--County), place_070 (State--County--County Subdivision--Place/Remainder), and place_172 (State--Consolidated City--Place within Consolidated City)
• Other datasets with corrected issues:
• 1850_cPAX - 1850 Census: Population, Agriculture & Other Data [US, States & Counties]
• In table NT21 (Persons at Learning Institutions by Type of Learning Institution), the data columns were jumbled for the middle 4 variables (AD1002: Teachers >> Public schools, AD1003: Teachers >> Academies and other schools, AD1004: Pupils >> Colleges, and AD1005: Pupils >> Public schools)
• 1998_2002_CBPb - 1998-2002 County Business Patterns (1997 NAIC Codes): Business Data [US & States]
• Most data values were truncated and/or erroneous in the 1999 state files
• 2011_ACS1 - 2011 American Community Survey: 1-Year Data
• Values for many nation- and region-level variables were truncated and/or erroneous. (NHGIS's internal files had shifted all values by 1 digit, causing the first digit of very large counts to appear in the wrong column in output files.)

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February 2017

New Look and New Name

We have launched a new look for the site along with a new name: IPUMS NHGIS.

NHGIS has always been part of the IPUMS family of projects. NHGIS, like other IPUMS projects, provides census and survey data integrated across time and space. Our updates bring NHGIS together with our other IPUMS projects to provide unique types of integrated data with a consistent look.

We still offer the same free data and data tools, and the basic features of the website and the Data Finder remain the same.

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January 2017

Change in Identification of Unnamed Areas

In NHGIS table data files, for records summarizing "remainder" areas (e.g., the part of a state or county that lies outside of any place), NHGIS previously identified the place name as "geog name n/a" (e.g., in the PLACE field). To correspond better with original source information, NHGIS now provides no text (i.e., blanks) for the place names of these records.

2011-2015 ACS 5-Year Summary File

The 2011-2015 American Community Survey (ACS) 5-Year Summary File has been released on NHGIS. Over 1,000 tables offer detailed cross-tabulations on age, sex, race, household structure, housing units, income, education, journey to work, and many other topics.

Tables are available for 87 geographic levels, down to census tracts and block groups.

Users should be aware that NHGIS has modified the original format of the ACS data to replace "." jam values with blanks for files in the comma delimited (.csv) output format. This was done to facilitate GIS processing. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2015 ACS technical documentation.

2015 GIS Boundary Files

NHGIS has released 85 new GIS boundary files based on 2015 TIGER/Line Shapefiles. The new files correspond to the geographic units of the 2015 American Community Survey 1-Year and 5-Year datasets. The release includes 52 state-specific files for block groups as well as 33 nationwide files for various geographic levels.

Data & Metadata Correction

NHGIS has corrected this error in its 1960 tract dataset:

• 1960_tPH - 1960 Census: Population & Housing Data [Tracts: Major Cities & Surrounds]
• The data columns for counts of renter-occupied housing units (in Table NT2), vacant housing units for rent or for sale (NT3), and occupied housing units with a nonwhite householder (NT4) were jumbled. NHGIS metadata has been corrected so that all variables in these tables now provide the correct data.

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December 2016

Data & Metadata Corrections

A new release of NHGIS metadata corrects several issues in NHGIS source tables, listed here by dataset:

• 1930_cAg - 1930 Census: Agriculture Data [US, States & Counties]
• A variable, labeled "All other field crops, irrigated, acres, 1929", has been moved from Table NT224 (Irrigated Tobacco, Cotton, Sugar, and Miscellaneous Crops -- Production by Type) to Table NT223 (Irrigated Tobacco, Cotton, Sugar, and Miscellaneous Crops -- Acreage by Type).
• 1935_cAg - 1935 Census of Agriculture: Agriculture Data [US, States & Counties]
• Originally, Table NT001 was designed to provide both 1930 and 1940 total population. In fact, the data reported for 1940 were incorrect, so the 1940 total has been removed from the table, and NT001 now provides only 1930 totals.
• Originally, Table NT043 (Farms with Occupied and Unoccupied Dwellings by Number of Dwellings) contained 7 variables, 2 of which were counts of dwellings, and 5 of which were counts of farms. The table has been split into 2 tables, one for each type of measured feature: NT043 (Dwellings on Farms by Occupancy) and NT044 (Farms by Number and Occupancy of Dwellings). In addition, the codes for all subsequent tables in the dataset have been incremented by one to adjust for the new NT044 table.
• A series of data columns, beginning in Table NT035 and continuing through NT050 (originally NT049), had been jumbled. NHGIS metadata has been revised so that all variables in these tables now provide the correct data.
• 1960_tPH - 1960 Census: Population & Housing Data [Tracts: Major Cities & Surrounds]
• The data columns for counts by employment status of all females (in Table NT39), nonwhite males (NT40), and Puerto Rican or Spanish Surname males (NT41) were jumbled. NHGIS metadata has been corrected so that all variables in these tables now provide the correct data.
• The labels and universes of several tables have been revised to use more consistent phrasing (e.g., "Nonwhite" instead of "Non-White") and more precise descriptions (e.g., indicating that NT54. Puerto Rican or Spanish Surname Persons by Marital Status is limited to persons of 14 years and over).
• 1970_Cnt3 - 1970 Census: Count 3 - 100% Data [Blocks & Tracts: Restricted to Areas with Block Statistics]
• The label of the dataset has been extended to describe the restricted geographic coverage of dataset. (Previously, the text in brackets described only "Blocks & Tracts".)
• 2000_SF3a - 2000 Census: SF 3a - Sample-Based Data [Areas Larger Than Block Groups]
• The data columns for the following tables were jumbled. NHGIS metadata has been corrected so that all variables in these tables now provide the correct data.
• NP042E. Civilian Noninstitutionalized Population 16 to 64 Years by Sex by Age Groups by Disability Status by Employment Status
• NPCT062D. Population 5 Years and Over Who Speak Languages Other than English at Home by Race by Age Groups by Ability to Speak English
• NPCT062E. Total Hispanic or Latino Population 5 Years and Over
• NPCT062F. Hispanic or Latino Population 5 Years and Over by Age Groups
• NPCT062G. Hispanic or Latino Population 5 Years and Over by Age Groups by Language Spoken at Home
• NPCT062H. Hispanic or Latino Population 5 Years and Over Who Speak Languages Other than English at Home by Age Groups by Ability to Speak English
• 2000_SF3b - 2000 Census: SF 3b - Sample-Based Data [Block Groups]
• As in dataset 2000_SF3a (as noted above), the data columns for Table NP042E were also jumbled in dataset 2000_SF3b. NHGIS metadata for this table were corrected in both datasets.

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November 2016

2015 ACS 1-Year Summary File

The 2015 American Community Survey (ACS) 1-Year Summary File has been released on NHGIS. Over 1,300 tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, transportation, and many other topics.

In the 1-year dataset, tables are available only for geographic areas with populations exceeding 65,000 persons.

Users should be aware that NHGIS has modified the original format of the ACS data to replace "." jam values with blanks for files in the comma delimited (.csv) output format. This was done to facilitate GIS processing. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2015 ACS technical documentation.

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October 2016

New Version Number & DOI

NHGIS has updated its recommended citation to be:

Minnesota Population Center. National Historical Geographic Information System: Version 11.0 [Database]. Minneapolis: University of Minnesota. 2016. http://doi.org/10.18128/D050.V11.0.

This citation includes two key changes:

1. The version number has changed from 2.0 to 11.0. The large leap in sequence reflects a change in the numbering system that NHGIS plans to use going forward. In the past, we incremented the version number only for a major site redesign in 2011. In the future, we plan to increment the version number annually, near the beginning of each calendar year, soon after we have released the latest 5-year ACS Summary Files. We have therefore updated the version number to be 11.0, reflecting that 2016 is the 11th year that NHGIS has been publicly available.
2. The citation now includes a Digital Object Identifier (DOI), representing a permanent registered index to this version of the NHGIS data and metadata. The current DOI will direct users to the current site. As we continue to increment the site version and DOI annually, past DOIs will direct users to an archive of the data and metadata as it existed at the time of each version increment, allowing users to reproduce results based on older versions of the system.

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September 2016

Time Series Tables, Release 7.0

This release adds 34 time series tables, including:

• New nominally integrated tables for Total Commuters, Commuters by Travel Time to Work, and Aggregate Travel Time to Work
• New tables (both nominally integrated and standardized to 2010) for:
• Persons by Hispanic or Latino Origin by Sex, Age, and Race in various combinations, including several detailed cross tabulations for White Non-Hispanic/Latino persons.
• Persons 18 Years and Over by Race Combination
• Occupied Housing Units (by Tenure) by Household Size

Data corrections:

• Release 7.0 corrects an error for all existing standardized-to-2010 tables. Previously, due to a text coding error in NHGIS's internal data files, all standardized time series supplied incorrect 2010 values for any area with a name that includes an accented character (e.g. ñ, á, ü, etc.). All data values are now correct.
• The formula for the hybrid model NHGIS uses to interpolate from 2000 blocks to 2010 units (as defined here) includes a coefficient of -.8057, which determines how much weight is given to the binary dasymetric model (based on road locations and imperviousness) relative to the target-density weighting model (based on 2010 block densities). Prior to Release 7.0, NHGIS's standardized 2000 data incorrectly used a coefficient of -.8056. This has been corrected in release 7.0. The adjustment has only very small effects overall.

Summary of new time series tables in Release 7.0   
(Stdzd. = standardized to 2010, Nom. Integ. = nominally integrated)

Bug Fixes--More Breakdown Values Available

Version 4.6 of the NHGIS web app, released on September 15, 2016, makes several minor improvements and corrections to the Data Finder. Most notably:

• For these two datasets, the Data Finder previously did not show all available breakdown categories, but now all categories are shown and selectable:
• 1990_SSTF04b: 1990 Census: SSTF 4b - Adults with Disabilities, Breakdown Data
• 1998_2002_CBPc: 1998-2002 County Business Patterns (1997 NAIC Codes): Business Data [ZIP Code Areas]
• It was previously possible for some selections on the Review & Submit page to be reset after a user selected specific extents for block and block group data requests. Now selections are preserved.
• Brief descriptions of breakdowns now use consistent case and ordering wherever they appear
• The ordering of categories within classifications is now universally consistent with the order of their usage within each table in all cases

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July 2016

Detailed Agricultural Census Data: 1920, 1925, 1930 & 1935

NHGIS has added 4 new datasets providing detailed summary statistics from the 1920, 1925, 1930 & 1935 Censuses of Agriculture. The new datasets (1920_cAg, 1925_cAg, 1930_cAg & 1935_cAg) include over 3,000 variables, organized into 594 tables, covering a broad range of agricultural subjects for counties, states, and the nation.

This is the first release in a planned series that will eventually extend NHGIS's collection to include detailed data from all U.S. Censuses of Agriculture through 2012. Previously, NHGIS included agricultural data only for decennial years from 1840 through 1950, and for 1920 and later, the NHGIS collection covered only a limited selection of subjects.

The new data (as with NHGIS's existing agricultural data) were compiled from printed sources by a team led by Michael R. Haines at Colgate University, including Price Fishback (University of Arizona) and Paul Rhode (University of Michigan). NHGIS researchers have additionally enriched the data by generating metadata that organize the variables into tables and associate each table with topics and categories.

A listing of all available variables and their sources (for both this release and upcoming releases) is available on the Tabular Data Sources page.

Time Series Tables, Release 6.1.1

This minor update to NHGIS time series tables mainly entails 3 types of changes:

1. Labels of 29 tables, all of which provide population counts for a particular race or ethnicity by age, or by sex by age, have been updated for consistency...
• The phrase "Persons of ..." has been replaced by "Persons Who Are ..."
• Descriptions of persons preceded by a race category (e.g., "White Persons") have been replaced by descriptions that begin with "Persons" (e.g., "Persons Who Are White").
2. The ordering of some race/ethnicity tables has been adjusted...
• Tables counting persons by Hispanic or Latino origin and of persons by Hispanic or Latino origin by race now precede all race by sex, race by age, and race by sex by age tables.
• Tables counting persons of a particular race by age or by sex by age are now ordered by the particular races first, then by years covered. E.g., all tables reporting persons who are White by age are now grouped together, followed by a group of tables reporting persons who are Black by age.
3. Several table notes and source document lists were edited for greater clarity and consistency.

Metadata Improvements

A new release of NHGIS metadata includes several small improvements. Most notably:

• The labels of 707 tables in 2000 Summary File datasets have been updated for greater clarity and consistency
• For consistency with most other datasets, the word "Total" now identifies only tables that report a single, comprehensive total and not any tables that distinguish multiple categories. E.g., "Total Population by Race" is now "Population by Race".
• The wording of the first 16 "by Race" tables in 2000_PL94171, 2000_SF1a and 2000_SF1b now clearly distinguishes which tables classify by "Number of Races" and which classify only "by Race". E.g., the label of NP003A in 2000_SF1a and SF1b was changed from "Population by Race" to "Population by Number of Races", and the label of NP003B was changed from "Population of One Race" to "Population of One Race by Race".
• In 2000_SF3a and 2000_SF3b, the labels of tables NP160F through NP160O had erroneously included "by Race of Householder". This phrase has been deleted in each case.
• An instance of the word "by" in the label of Table NP027M in 2000_SF1a and SF1b had been in upper case and is now in lower case.
• The labels of 3 tables in the 1860_cPAX dataset (NT4, NT5, and NT6) now include "Slave Status", and each is now also associated with the Slavery topic. Previously, these tables appeared only to cover Race (by Age and by Sex), but the tables importantly also include "Slave" and "Free colored" categories.

Improved Universal MPC/IPUMS Registration System

Updates to the Minnesota Population Center's universal user account management system, supported with a new version of the NHGIS web app (4.5), enable users to access all MPC/IPUMS data projects, including NHGIS, through a single account.

The previous system required users to update each of their MPC/IPUMS data accounts (including NHGIS) separately on an annual basis. The new system requires only a single registration update for all MPC/IPUMS projects at one time, once a year.

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December 2015

2014 ACS 5-Year Summary File Release

The 2014 American Community Survey (ACS) 5-Year Summary File has been released on NHGIS. Over 1,000 tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, transportation, and many other topics.

In the 5-year dataset, tables are available at the block group geographic area and larger.

Users should be aware that NHGIS has modified the original format of the ACS data to replace "." jam values with blanks for files in the comma delimited (.csv) output format. This was done to facilitate GIS processing. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2014 ACS technical documentation.

New 2014 GIS Boundary Files

NHGIS has released 85 new GIS boundary files based on 2014 TIGER/Line Shapefiles. The new files correspond to the already released 2014 American Community Survey 1 and 5-Year datasets. In addition to 52 state-specific files for block groups, the release includes of 33 nationwide files for various geographic levels.

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November 2015

Improvements to Table File Structures & Content

Version 4.3 of the NHGIS web app, released on November 30, 2015, makes several updates to the structure and content of source table and time series table output files, including:

• Elimination of blank geographic name columns in source table extracts
• New "NO DATA" indicators in codebooks when no data are available for some selected geographic extents
• Separate FIPS and NHGIS state and county codes in nominally integrated time series table files
• NHGIS previously supplied only a single version of state and county codes without an explicit indication of whether they were FIPS or NHGIS codes
• Standardization of the geographic names and codes provided in time series table files
• In all time series table layouts, the geographic info is now generally "integrated" info (consistent across all time), and the column descriptions state explicitly which columns contain integrated info and which contain year-specific info.
• Correction of a bug that omitted geographic codes and names for some records in some nominally integrated time series tables
• Revision of some geographic names in nominally integrated time series tables from 2013 names back to 2012 names
• Some names had been updated to 2013 versions when we added 2013 ACS data to NHGIS, but because the latest year in time series tables is currently 2012, the 2012 names are more appropriate

Updates to Account Management System & Time Series Table Layout Options

Version 4.2 of the NHGIS web app, released on November 18, 2015, makes two notable changes to the user experience:

1. The user account management system is now an independent web app that is standardized for all Minnesota Population Center data projects. Account sign in, creation, and password changes are run through this system.
2. The ordering of time series table layout options is now time-varies-by-column, -by-row, and -by-file, and the default is -by-column. Previously, the default was -by-file and the ordering was -by-file, -by-row, and -by-column.

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October 2015

2014 ACS 1-Year Summary File Release

The 2014 American Community Survey (ACS) 1-Year Summary File has been released on NHGIS. Over 1,300 tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, transportation, and many other topics.

In the 1-year dataset, tables are available for geographic areas exceeding the U.S. Census Bureau minimum population requirement of 65,000 persons.

Users should be aware that NHGIS has modified the original format of the ACS data to replace "." jam values with blanks for files in the comma delimited (.csv) output format. This was done to facilitate GIS processing. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2014 ACS technical documentation.

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September 2015

Block and Block Group Level Adjustments

Standardization of 1990 block level

NHGIS has altered the exact hierarchy and coding of its 1990 census block geographic summary level to be consistent with the block level used in 1970 and in years after 1990.

Previously, NHGIS's 1990 block level (identified as "block_9100") included block groups in its hierarchy, and the unique identifiers (GISJOIN codes) for 1990 blocks included the block group code.

This practice was consistent with the block summary level definition from 1990 Census source files, but in later years, the Census's standard block level has dropped the block group code. The single-digit block group code is in fact redundant because it matches the first digit of each 3- or 4-digit block code, which is always included in complete block identifiers (along with state, county, and tract codes).

Dropping block groups from the 1990 block level has no effect on the content of NHGIS tables and boundary files except in the GISJOIN codes, which no longer include block group codes. Users who obtained 1990 block data from before this change will not be able to join the older data to newer data without adjusting the GISJOIN codes to match. Users may also resubmit older extract requests to obtain the same data with updated codes.

The primary benefit of this update for NHGIS users is that 1990 block data should now be easier to find and select in the NHGIS Data Finder because the 1990 level is no longer distinct from the standard block level (identified as "block").

Changes to block and block group level labels to indicate 1980 restrictions

NHGIS provides tables for 1980 blocks and block groups using geographic levels that are distinct from the standard block and block group levels used in other years. With this release, we have adjusted the labels of these levels (along with some block levels used in 2000 and 2010) to clarify exactly which levels are available for which years and datasets.

The updated labels for 1980 block and block group levels additionally indicate some unique restrictions:

• Block data from 1980 Summary Tape File 1 (NHGIS's "1980_STF1" dataset) are divided into two compound geographic levels:
• "block_02198" includes county subdivisions in its hierarchy and is available only for states that have minor civil divisions (MCDs)
• "block_02598" does not include county subdivisions in its hierarchy and is available only for states that do not have MCDs
• Block group data from 1980 Summary Tape Files 1 and 3 (NHGIS's "1980_STF1" and "1980_STF3" datasets) are available only in a compound level ("blck_grp_01598") that includes county subdivisions and places in its hierarchy. This level is also available only for Urban or Rural spatial breakdowns and not for the default "Total area" breakdown.

Time Series Tables, Release 6.1, and Related Website Updates

With this release, NHGIS has extended its 65 geographically standardized tables to provide 2000 and 2010 data for 2010 census units at 9 more geographical levels (in addition to existing data for 2010 census tracts):

• Block groups
• ZIP Code Tabulation Areas (ZCTAs)
• Core based statistical areas (including both metropolitan and micropolitan statistical areas)
• Urban areas
• Congressional districts (as defined for the 110th-112th Congresses)
• Places
• County subdivisions
• Counties
• States

Accompanying this release are several updates to the user interface and extract system, most notably:

• New "geographic level" details pop ups, available by clicking on linked geographic level labels or abbreviations in the Data Finder
• The addition of an "NHGISCODE" Integrated Geographic Unit Code in all data files for nominally integrated time series tables at the tract, place, or county subdivision levels
• Previously, this code was available only in files using the Time Varies by Column layout. Files for other layouts provided only "GISJOIN" codes. Unlike GISJOIN codes, the NHGISCODE code is the same for all nominally integrated units across time (matched by name and/or code). It is supplied only for the 3 geographic levels for which NHGIS has matched units with differing codes across time. At other levels (county, state, etc.), the existing "GISJOIN" code acts as the match code.

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August 2015

Time Series Tables, Release 6.0

With this release, NHGIS now provides time series tables using 2 types of geographic integration. Previously released time series tables used only nominal integration. NHGIS now also provides 65 tables that use geographical standardization. Specifically, the standardized tables in Release 6.0 provide 2000 and 2010 data for 2010 census tracts. We plan to release standardized tables for several more 2010 census geographic levels soon.

Because the 2000 statistics in the new standardized tables are derived from 2000 census block data, the topics covered by the tables are limited to those for which 2000 block data are available. This excludes subjects covered only in the 2000 census long-form questionnaire (e.g., income, poverty, education, marital status, place of birth, etc.) as well as some subjects from the 100%-count short-form data that were not tabulated for blocks (e.g., urban/rural status).

In the process of assembling the new standardized tables, we undertook a thorough review of our existing nominally integrated tables for all tabulation types that use 100%-count 2000 source data. As a result, this release also includes 21 new nominally integrated time series tables that provide combinations of categories, years, and/or geographic levels that were previously unavailable. We also made significant revisions to 17 existing tables (detailed below), and we dropped 2 tables (B19: Persons 65 Years and Over in Group Quarters, and B20: Persons 65 Years and Over in Group Quarters by Group Quarters Type [2]). The dropped tables became redundant after other tables (AY6 and AH4) were extended to cover the same set of information.

Summary of new and revised time series tables in Release 6.0   
(Stdzd. = standardized to 2010, Nom. Integ. = nominally integrated)

Changes to nominally integrated time series tables in Release 6.0

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February 2015

New 2013 GIS Boundary Files and Other New & Updated Files

NHGIS has released 85 new GIS boundary files based on 2013 TIGER/Line Shapefiles. The new files correspond to the already released 2013 American Community Survey 1, 3, and 5-Year datasets. In addition to 52 state-specific files for block groups, the release includes of 33 nationwide files for these geographic levels:

• 5-Digit ZIP Code Tabulation Area (ZCTA)
• Alaska Native Regional Corporation
• American Indian Area/Alaska Native Area/Hawaiian Home Land (in 3 formats: all areas; reservation or statistical entity only; and off-reservation trust and home lands only)
• Block Group
• Census Tract
• Combined Statistical Area
• Congressional District (113th Congress)
• Consolidated City
• County
• County Subdivision
• Division
• Metropolitan Division
• Metropolitan Statistical Area/ Micropolitan Statistical Area
• Nation
• New England City and Town Area (and Combined NECTA and NECTA Division files)
• Place
• Public Use Microdata Area (PUMA)
• Region
• School Districts (Unified, Elementary and Secondary files)
• State
• State Legislative Districts (Lower Chamber and Upper Chamber files)
• Subminor Civil Division
• Tribal Block Groups, Tribal Census Tracts, and Tribal Subdivisions
• Urban Area

In addition to the complete set of 2013 GIS boundary files, 6 existing files were improved and 3 additional files were added.

Improved GIS files in this release include:

• Standard Metropolitan Statistical Area (SMSA) files for 1950-1980 were modified to include the metro area name in the attribute table.
• Primary Metropolitan Statistical Area (PMSA) files for 1990-2000 were modified to include an additional 9 character GISJOIN field, entitled GISJOIN3. This new field corresponds to tabular data from the most popular 1990 and 2000 datasets. The existing 5 character GISJOIN field was not changed and still corresponds to certain, less common datasets.

Additional, new GIS files in this release include:

• 2009 Subminor Civil Division (Puerto Rico only) with the 2009 TIGER/Line+ basis.
• 2000 American Indian American Indian Area/Alaska Native Area/Hawaiian Home Land (reservation or statistical entity only) with the 2000 TIGER/Line+ basis.
• 1970 Standard Metropolitan Statistical Area (by State) with the 2000 TIGER/Line+ basis. This file more accurately reflects the corresponding tabular data.

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December 2014

2013 ACS 5-Year Summary File Release

The 2013 American Community Survey (ACS) 5-Year Summary File has been released on NHGIS. Over 1,000 tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, transportation, and many other topics.

In the 5-year dataset, tables are available at the block group geographic area and larger.

Users should be aware that NHGIS has modified the original format of the ACS data to replace "." jam values with blanks for files in the comma delimited (.csv) output format. This was done to facilitate GIS processing. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2013 ACS technical documentation.

Data Finder Updates

Version 3.9 of the NHGIS Data Finder web application includes several interface improvements and bug fixes. The most significant changes:

• Codebooks for block and block group data tables now include a listing of selected state extents (if not all states were selected)
• If a user makes selections on the Data Options or Review & Submit pages, the selections are preserved even if the user goes back in the process and returns.
• The pop-up window that presents source table selections from the Data Options page now includes "Cancel" and "Submit" buttons
• Font styles were adjusted to be more consistent throughout

Table Revisions

A new release of NHGIS table metadata includes these revisions:

• Labels for tables and variables in County Business Patterns datasets are now more precise and consistent with style used elsewhere. E.g., tables previously labeled "Employment Size Class by Establishments" are now labeled "Establishments by Employment Size Class", etc.
• Tables reporting dollar figures in the County Business Patterns datasets and the 1920-1936 FDIC Bank Deposit dataset are now scaled properly. These tables previously presented data in thousands of dollars, but to make the scaling explicit in the data, the NHGIS extract system now multiplies all figures by 1,000, producing true dollar figures.
• In time series tables for county subdivisions in the time-varies-by-column layout, 1970 Hampton Township, Rush County, Kansas, is now separated onto its own row. It had previously been matched to Hampton-Fairview township for later years.

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November 2014

New 2009 GIS Boundary Files and Other Updated Files

NHGIS has released 116 updated or new GIS Boundary files. All GIS Boundary files with a basis of TIGER/Line 2009+ are included in this new release, as are 32 state-specific block boundary files with basis of TIGER/Line 2010+ and two files with basis of TIGER/Line 2008+ .

Many of the newly released NHGIS files with basis of TIGER/Line 2009+ correspond to the 2009 ACS datasets. However, the block group and census tract boundaries derived from 2009 TIGER/Line files represent Census 2000 definitions of those areas. Most of the block group and census tract tables from the 2009 5-Year American Community Survey (ACS) Summary File correspond to the Census 2000 definitions, but according to ACS documentation, "in 19 counties from 8 different states, many of the census tracts and block groups used to tabulate and present the 2005-2009 ACS 5-year estimates are either those submitted to the Census Bureau for the 2010 Census, or a preliminary version of 2010 Census definitions." More information on these discrepancies, including a listing of affected counties, is available here. In addition, these 2009-based boundary files were built, in part, with a coastline created with 2010 TIGER/Line features.

Freshly revised 2010 state-specific block boundary files reflect a small change to those blocks located in coastal regions. The area field, Shape_Area, was recalculated as it previously did not account for the water area clipped from the coast in the final product.

The 1990 and 1980 county level GIS boundary files with the 2008 TIGER/Line+ basis were updated to reflect a small coding correction for Kalawao County, Hawaii.

2013 ACS 3-Year Summary File Release

The 2013 American Community Survey (ACS) 3-Year Summary File has been released on NHGIS. Over 1,300 tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, transportation, and many other topics.

In the 3-year dataset, tables are available for geographic areas exceeding the U.S. Census Bureau minimum population requirement of 20,000 persons.

Users should be aware that NHGIS has modified the original format of the ACS data to replace "." jam values with blanks for files in the comma delimited (.csv) output format. This was done to facilitate GIS processing. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2013 ACS technical documentation.

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October 2014

Data Finder Updates

Version 3.8 of the NHGIS Data Finder web application includes several interface improvements and bug fixes. The most significant changes:

• The Years filter interface now separates 5-year ranges, 3-year ranges, and school years into separate groups
• The listing of geographic levels in dataset details pop-ups is more cleanly formatted
• The Review and Submit page has been reorganized to use an ordering consistent with other pages
• The case of some headings was changed, so the "data finder" has officially become the "Data Finder"!
• The Extracts History page will now reload faster
• To preserve server resources, requests will not be accepted if they duplicate another request already in process or a request that previously timed out

Time Series Tables, Release 5.0

Release includes 17 new tables for 7 tabulation types:

2013 ACS 1-Year Summary File Release

The 2013 American Community Survey (ACS) 1-Year Summary File has been released on NHGIS. Over 1,300 tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, transportation, and many other topics.

In the 1-year dataset, tables are available for geographic areas exceeding the U.S. Census Bureau minimum population requirement of 65,000 persons.

Users should be aware that NHGIS has modfied the original format of the ACS data to replace "." jam values with blanks for files in the comma delimited (.csv) output format. This was done to facilitate GIS processing. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2013 ACS technical documentation.

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September 2014

2009 ACS 5-Year Summary File Release

The 2009 American Community Survey (ACS) 5-Year Summary File has been released on NHGIS. Nearly 1,000 tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, transportation, and many other topics.

In the 5-year dataset, tables are available at the block group geographic area and larger.

Users should be aware that NHGIS has modified the original format of the ACS data to replace "." jam values with blanks for files in the comma delimited (.csv) output format. This was done to facilitate GIS processing. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2009 ACS technical documentation.

Data Finder Updates

Version 3.7 of the NHGIS Data Finder web application includes several interface improvements and bug fixes. The most significant changes:

• Pop-ups listing long breakdown lists (such as the Industry breakdowns for County Business Patterns datasets) load much faster.
• Large extract requests are now allowed to run 10 hours before timing out, instead of the previous 8 hours.
• The "How to use the data finder" link now links to the latest (August 2014) version of the "Using NHGIS: An Introduction" tutorial.

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April 2014

Improved Breakdown Codes

NHGIS has made several improvements to its breakdown coding scheme. (See the FAQ for an explanation of NHGIS breakdowns.) The most significant changes:

• Previously, breakdown codes in NHGIS data files were all 4 characters long. Now, to reduce noise in column identifiers, breakdown codes may be 2, 3, or 4 characters long depending on how many characters are needed to uniquely identify all breakdown combinations in use by a given dataset.
• Previously, the ordering of codes was somewhat arbitrary, determined by the sequence of breakdowns in the NHGIS metadata database. Now, codes are ordered according to their original logical sequence.
• Previously, in multi-year datasets like County Business Patterns, codes varied by both breakdown and year, so a single industry breakdown category would have different codes in different years. Now, within each dataset, a breakdown has a single code across all years, making it easier to identify files and columns associated with the same breakdown.

Note: as a consequence of these updates, most breakdowns have new codes. Users who would like to re-obtain previous data requests with codes that match the current codes may simply resubmit their older requests through the Extracts History page.

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February 2014

Time Series Tables, Release 4.1

This release updates all tables that include American Community Survey (ACS) data to use 2012 5-year data instead of 2011 5-year data.

Because the 2008-2012 period is centered on the year 2010, we believe it is the most suitable ACS period for use in the NHGIS's decade-interval time series. Therefore, this update should be the last of its kind. NHGIS may in the future release new time series tables that include ACS data from other time periods, but there are no plans to again swap old data with new.

For almost all time series, there are 2012 ACS statistics that correspond exactly to the previously used 2011 ACS statistics, with one exception. It was not possible to extend the time series of persons born in (former) Yugoslavia because the 2012 ACS Summary Files provide no separate count of persons born in Yugoslavia.

Accordingly, for effective comparability, the (former) Yugoslavia time series is now provided in a new, separate table named "Persons Born in (Former) Yugoslavia," which is the only time series table to use 2007-2011 ACS data. In the 6 place-of-birth tables that had previously provided a distinct count for (former) Yugoslavia, the subgroup is now included within "Other Europe" or "Other Eastern Europe" counts, as appropriate for each table.

Also in this release, the table of "Persons 16 Years and Over by Labor Force and Employment Status [6]" has been extended to cover tracts, county subdivisions, and places.

2012 ACS 5-Year Summary File Release

The 2012 American Community Survey (ACS) 5-Year Summary File has been released on NHGIS. Over 1,000 tables offer detailed cross-tabulations of age, sex, race, household structure, housing units, income, education, transportation, and many other topics. This 2012 ACS release also includes tables on health insurance coverage. This is the first time the topic has been available in a 5-Year ACS.

In the 5-year dataset, tables are available at the block group geographic area and larger.

Users should be aware that NHGIS has modified the original format of the ACS data to replace "." jam values with blanks for files in the comma delimited (.csv) output format. This was done to facilitate GIS processing. These jam values appear within certain tables for records with too few observations to tabulate. Users interested in obtaining the original "." values should request data in the fixed width format when finalizing their data extracts. Additional information on jam values can be found within the 2012 ACS technical documentation.

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December 2013

Revised and New GIS Boundary Files

NHGIS has released updated GIS Boundary files that reflect various, small coastline revisions made by NHGIS. All 2010 and 2011 GIS Boundary files with a basis of TIGER/Line 2010+ or TIGER/Line 2011+ are included in this update except those state-specific block and block group GIS boundary files for the non-coastal states.

NHGIS has also released a new 2011 nationwide block group file to correspond with the preexisting 2011 state-specific block group files, as well as 2012 state-specific block group files to correspond with the preexisting 2012 nationwide block group file.