Maintained by the U.S. Census Bureau. Factfinder is the online portal for 1990 and 2000 census data. Users can query and map large amounts of census data at every level of geography. Data can also be downloaded in a spreadsheet format and transposed for use in a GIS application. Maps may also be downloaded.
Comprehensive website produced by the University of Washington. Lots of links and information on economic and business geography. Defines the area and offers suggestions for further research. Recommended for a newcomer interested in learning more.