Steven Manson, Jonathan Schroeder, David Van Riper, Tracy Kugler, and Steven Ruggles. IPUMS National Historical Geographic Information System: Version 15.0 [Database]. Minneapolis, MN: IPUMS. 2020. http://doi.org/10.18128/D050.V15.0
The National Historical Geographic Information System (NHGIS) provides free online access to summary statistics and GIS boundary files for U.S. censuses and other nationwide surveys from 1790 through the present. GIS files include: counties and states since 1790, census tracts since 1910, metropolitan areas since 1950, place and county subdivision boundaries since 1980, place points since 1900, all standard census reporting areas since 1990, 200 and 2010 centers of population for four geographic levels, and SABINS school attendance areas for 2009-12. Summary tables from decennial censuses and the American Community Survey include county and state tables since 1790; census tract tables since 1910; and tables for all original census summary levels, down to census blocks, since 1970. Highlights of additional summary tables include County Business Patterns data (annual, 1970-2002), vital statistics for counties and states (births and deaths: annual, 1915-2007; marriages and divorces: selected years, 1867-2010), agricultural census data (1840-1950), religious bodies data (1850-1952), manufacturing census data (1840-1940), and 2010 census data for SABINS school attendance areas. NHGIS also includes geographic crosswalks summarizing associations between 190-2010 census blocks, environmental summaries describing land cover by county and census tract and climate characteristics by county, and time series tables providing comparable statistics from multiple source years with standardized categories and geography. NHGIS data are available through an online access system and are available free of charge to registered users at http://nhgis.org.
Past versions of data are available by request to registered IPUMS-NHGIS users. Please contact firstname.lastname@example.org. Archived versions of the data have been stored in fixed-format files with accompanying documentation and index files.
IPUMS-NHGIS data are continually revised. We archive annual snapshots and document changes between snapshots. The changes made to Version 15.0 before we archived Version 16.0 occurred between 8-1-2020 and 6-22-2021 as documented in the Release Log [https://www.nhgis.org/documentation/release-log].