http://tags.library.upenn.edu/project/20148/data PennTags Feed http://tags.library.upenn.edu/makerecord/ered/19954 http://tags.library.upenn.edu/makerecord/ered/19954 <div class="mlacite">Social Explorer<br />The Social Explorer produces maps and reports of US Census Tract level data from 1940-2000. Using high quality maps and data, they make available the full contents of the tract data for the United States for the full period. Reports include aggregated totals and the system allows for slideshows demonstrating change over time. The data can also be exported as excel spreadsheets for easy reuse.<br /></div> http://tags.library.upenn.edu/makerecord/url/20150 http://tags.library.upenn.edu/makerecord/url/20150 Shapefiles and data at the census tract, county, state, and other geographic levels going back to 1790 for counties, and 1910 for tracts. Also includes some data for downloading.