Summary
The SABINS GIS shapefiles contain 2009-2010, 2010-2011, or 2011-2012 school-year data delineating school attendance areas by grade for selected school districts throughout the U.S. The last two characters of any file name designate a grade (i.e., 00 is Kindergarten, 01 is first grade and 12 is twelfth grade).
These data were collected and processed as part SABINS data infrastructure project which was funded by grants from the National Science Foundation (Award # SES-0927794, SES-0921279, SES-1123727) to create geography delineating school attendance boundaries for the largest school districts in the United States and for any school districts for which we could collect state-wide information from a state's Department of Education.
Primary sources
Original source information that were used to create these boundary files were collected in two primary formats:
- GIS data from local school districts, county/municipal GIS offices and private consulting firms
- These agencies used a wide-variety of geography to create these files (e.g., local cadastral or parcel data or digital imagery) and considerable care was taken to ensure that these original files accurately delineated the school catchment areas that a school district intended them to represent.
- Analog data such as narrative/legal descriptions of boundaries, lists of street segments served by each school boundary or paper maps of school attendance boundaries that depicted the boundaries.
- U.S. Census Bureau 2010 TIGER/line features (which consist of streets, hydrography, railways, etc.) were the primary source of information used to digitize analog information. This practice works well as most school attendance boundaries align with streets, railways, water bodies and similar line features included in the 2010 TIGER/line "edges" files.
- In those few cases in which a portion of a school attendance boundary serves both sides a street we use USGS DOQQ imagery to approximate the property lines of parcels.
The data digitized from analog maps and verbal descriptions do not conform to cadastral data, and many of the original GIS files created by school districts also do not conform with cadastral or parcel data.
Block rectification
All school attendance boundaries are "block-rectified" to 2010 TIGER/Line blocks such that the outline of every school attendance area conforms to the edges of census blocks.
Specifically, for the revised boundary files released in April 2013, to assign blocks to school attendance areas, we select all census blocks that belong to a particular school district according to TIGER/Line file attributes. Then, we use the NEAR tool in Esri ArcGIS to assign the selected blocks to school attendance areas for the same school district. If a block associated with a district falls outside all school attendance areas for the district, the NEAR command assigns the census block to the closest school attendance area based on Euclidean distance. This prevents mismatches between TIGER/Line school district definitions and SABINS school attendance areas.
The purpose of block-rectifying school attendance boundaries is to estimate population characteristics residing within school attendance boundaries by using census block data. Because of block rectification, school attendance boundaries cannot be used to identify specific addresses that are served by a school.
Supplementary attributes
Also in the April 2013 release, the MPC added attributes for each school attendance area identifying the counts of Private, Magnet, and Charter schools that fall within an attendance boundary. The IND_COINCI, SPECIAL_CA, IND_OPEN_E, and IND_MULTIP attributes that appeared in previous versions of SABINS files have been dropped.
Area-to-school relationships
In many school districts, two or more schools may serve a single school attendance area (a one-area-to-many-schools relationship) or two or more schools may serve overlapping areas (a many-schools-to-many-areas relationship). In all cases, a single SABINS polygon represents an area served uniformly by a unique set of schools.
As a consequence, a single SABINS polygon may be associated with multiple schools, and a single school's attendance area may be comprised of multiple SABINS polygons.