http://tags.library.upenn.edu/tag/census+census2000 PennTags Feed for /tag/census+census2000 PennTags Feed http://tags.library.upenn.edu/makerecord/url/7223 http://tags.library.upenn.edu/makerecord/url/7223 ERS/USDA Briefing Room - Measuring Rurality: Rual-Urban Commuting Area Codes The Rural-Urban commuting area (RUCA) codes, a detailed and flexible scheme for delineating sub-county components of the U.S. settlement system, have been updated using data from the 2000 decennial census. http://tags.library.upenn.edu/makerecord/url/7212 http://tags.library.upenn.edu/makerecord/url/7212 Public Use Microdata Areas Cartographic Boundary Files Descriptions and Metadata - U.S. Census Bureau i think this is the puma shapefile<br />