Enhanced Historical Land-Use and Land-Cover Data Sets of the U.S. Geological Survey: polygon format files
This data set depicts land use and land cover from the 1970s and 1980s 
and has been previously published by the U.S. Geological Survey (USGS) 
in other file formats. This version has been reformatted to other file formats 
and includes minor edits applied by the U.S.  Environmental Protection 
Agency (USEPA) and USGS …