Atlas of Historical County Boundaries

Douglas Knox writes, “Thought you might be interested to know the Newberry recently completed the digital Atlas of Historical County Boundaries. It has historical boundaries for every county in the U.S., dated to the day, freely available online for noncommercial use in a number of forms.” Those forms include online interactive maps, shapefiles, KMZ for Google Earth, and PDFs; they cover every county since the first one was created in 1634.