2010 Census Urban and Rural Classification and Urban Area Criteria
Explains the U.S. Census Bureau's classification of rural and urban areas for the 2010 Census. Features tables comparing 2000 and 2010 Census data for rural and urban areas, including Urbanized Areas and Urban Clusters. Offers links to data files which provide the percent rural/urban by state and county for 2010.
U.S. Census Bureau
County-by-county data · Rural definitions · State-by-state