IPUMS Center for Data IntegrationThe National Historical Geographic Information System (NHGIS) provides easy access to summary tables and time series of population, housing, agriculture, and economic data, along with GIS-compatible boundary files, for years from 1790 through the present and for all levels of U.S. census geography, including states, counties, tracts, and blocks.https://www.nhgis.orgengPublicNational government recordsCensusNational Historical Geographic Information System (NHGIS)WebsitesContinually updated resourceUniversity of Minnesota