Provides comprehensive data and downloadable shapefiles on the formation, development, and fluidity of county borders within the territory of the United States from 1629 to 2000.
First launched in 2010, the Atlas represents more than twenty years of work compiling county lines from research in state laws and other primary sources. Offers comprehensive information for counties in all fifty states. Covers history, politics, geography, journalism, law, and genealogical studies.
This resource is open to the general public.