The U.S. Census Bureau publishes its findings on Census.gov, although I often find it easier to get Census Bureau data for a particular location using using State & County Quick Facts.
You can design your own table of census bureau data using The American Factfinder.
For more information, call the Census Bureau (202-264-0634) or read the extensive information on the Bureau's web site.
American Community Survey: As of 2010, the Decennial Census has been limited to a short form designed primarily to count the population. The more detailed information once collected on the "long form" is now gathered on a continuous basis in the American Community Survey. The Survey began in 1996 and is also administered by the Census Bureau.
Historical Census Data: The Census Bureau is allowed to release data from individual families after 72 years.
Census records from the 1940 census are posted by National Archives and Records Administration. Ancestry.com provides a search by name feature for both the 1930 census and the
For older information, the Census Bureau posts selected historical census data back to 1790. Historical data (pre-2011) can also be found in old editions of The Statistical Abstract of the United States, the State and Metropolitan Area Data Book and the County and City Data Book; check Worldcat to find libraries holding back editions. Ancestry.com has a U.S. Federal Census Collection going back to 1790, including a recreation of the 1890 Census that was destroyed in a fire (subscription).
Foreign Census Data: Links to the Web sites of foreign census agencies are posted at www.census.gov/main/www/stat_int.html. Ancestry.com has UK Census Collection. and a Canadian Census Collection (subscription).