The offical site of the U.S. Census Bureau includes both the Decennial Census, 1990-2000, and the American Community Survey, an on-going survey. Both the Decennial Census and ACS have demographic data at the national, state, county, and place levels, but ACS does not include small cities and towns. Data is presented in tables which can be downloaded.

This site contains links to all of the Census Bureau's online data by category: people & households, business & industry, geography, decennial census (American FactFinder), economic indicators, plus quick facts. Both national and state data are available. Data is available in tables and can be downloaded.

This site offers original raw data from the U.S. Census Bureau which can be downloaded and manipulated using SAS, SPSS, or Stata programs.

This site provides one-stop access to U.S. federal, state, and local data and maps from multiple U.S. government agencies.  Data categories include agriculture, biology, business, demographics, environment, health, geology, inland water, transportation, etc.  Users can register (free) to take advantage of personalized options.

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 two-part publication, available online in PDF format, contains statistics about the United States from colonial times to 1970. Issued by the Census Bureau, the publication includes an explanation of the data as well as the actual statistical tables.

This is the source data for the Historical Census Browser site.  Data can be downloaded and manipulated using SAS or SPSS

The official U.S. immigration statistics are included in the Yearbook of Immigration Statistics on this site. Tables contain historical data, many as far back as 1820. Sections of the Yearbook can be downloaded in PDF format, or individual tables are available in Excel. The site also contains useful links to related resources.

The Integrated Public Use Microdata Series (IPUMS) consists of 39 samples of U.S. population from the 1850-2000 decennial censuses and the 2000-2006 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.

MMWR is compiled by the Centers for Disease Control from data supplied weekly by state health departments. Articles and data are related to reportable illnesses and deaths. Data, presented in tables, is available at the national and regional levels as well as for larger cities (e.g. Wichita, Kansas City).

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.

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.

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.

This site presents annual data on U.S. births, deaths, marriages and divorces. Historic volumes for 1890-1994 can be viewed or downloaded as PDF files. Individual natality tables for 1994-2002 can be viewed online or downloaded as PDF files. The CDC is creating a new site called VitalStats for current data; VitalStats provides more options for data display and manipulation, however the expanded data options require users to login (free).