databases of statistical information
Census and Demographics
U.S. Census Bureau
The main page for accessing information on the 2010 census.
The Census Bureau's gateway site to population, housing, economic and other data, down to a city, zip code census tract and block level. Select Data Sets in the menu on the left to see a list of available data.
National database of selected Census, American Community Survey and other economic, business, government and geogrpahical data for all states and counties, and for cities and towns with +25,000 people.
The U.S. Census Bureau provides access to databases related to building permits, imports/exports, employment and earnings (by county), occupational breakdowns by race, and other info.
The U.S. Census Bureau provides map files that can be used to display census data. They can be merged with data in GIS programs or online mapping sites such as GeoCommons. Files for the 2010 Census will be available beginning in Feburary 2011.
Minnesota Population Center
IPMUS, the Integrated Public Use Microdata Series at the University of Minnesota compiles current and historic U.S. Census data at an online site that makes it easy to create custom data tables on a national, state and local level.
IRS
U.S. Population Migration Data
Numbers of people moving into or out of counties and states in the United States.
California Department of Finance
Demographic data on California, including county data. Many of the datasets are downloadable as text or spreadsheet files.
Association of Bay Area Governments
Census data for Bay Area counties, cities, census tracts and blocks, from the Association of Bay Area Governments in partnership with the Metropolitan Transportation Commission.

