TIGER/Line Shapefile, 2009, state, Pennsylvania, Current State and Equivalent State-based
The TIGER/Line Shapefiles are an extract of selected geographic and cartographic information from the Census MAF/TIGER database. The Census MAF/TIGER database represents a seamless national file with no overlaps or gaps between parts. However, each TIGER/Line Shapefile is designed to stand alone as an independent data set or the shapefiles can be combined to cover the whole nation.
U.S. Department of Commerce and U.S. Census Bureau, Geography Division