Official site of the U.S. Census Bureau. Includes the Decennial Census, 2000-2010, and the American Community Survey, an on-going survey. Both have demographic data at the national, state, county, and place levels, but ACS does not include small cities and towns. Data is in tables which can be downloaded.
Contains links to all of the Census Bureau's online data by category: people, business, geography, decennial census (American FactFinder), press releases, and quick facts. Both national and state data are available. Data is available in tables and can be downloaded.
Consists of 39 samples of U.S. population from the 1850-2010 decennial censuses and the 2000-2010 American Community Surveys. Microdata includes information about individuals and households. However, by law, data since 1940 must preserve confidentiality, so no names or addresses are included for those files, some data has been restricted, and no places with fewer than 100,000 inhabitants (250,000 for 1960 and 1970) are included. Users must register (free) to download raw datasets, but the site provides the ability for some online tabulation.
This site provides selected tables at the national, state, and county levels. "Map-it" feature provides links to interactive maps of the data. Data cannot be downloaded.
This annual publication has been one of the primary U.S. statistical sources for 130 years. Arranged by topics (population, vital statistics, income, agriculture, manufacturing, etc.), each section contains many tables of data.
NHGIS (National Historical Geographic Iniformation System)
This site provides access to data and GIS files for historic census and business titles. Users must register before accessing data, but there is no charge. The site provides easy-to-read charts of data and boundary file availability. Users can select the date, geography, and variable(s) for desired data. Boundary files for GIS use are available either via the Shape Finder option, or in the last step of the data downloading process. Boundary files are not available for all variables and geographies. Download options include SPSS, SAS, Stata, CSV file, GIS CSV file, and shapefiles.
Contains more than 18,000 maps, hundreds of profile reports, 40 billion data elements, 335,000 variables, and 220 years of data. Interactive mapping and reporting tools let you explore a vast array of demographic data quickly and easily.
This site contains worldwide data on population, migration, urbanization, resources, environment, and development. The country profiles in the PRED databank contain more detailed information. Data is presented in tables and can be downloaded in either Excel or .csv format.