A sample of responses from the U.S. Census Bureau's American Community Survey.
Maintained by the Centers for Disease Control (CDC). Includes both statistics and microdata.
Time-series data on voting behavior and political opinions back to 1948.
Data from several studies related to migration in the United States and Latin America.
Question-level/variable-level searching of the data archives of 20 European countries. This is the most comprehensive source for sets of European survey data. The catalog links to the sites of the national data archives, some of which require registration or place other restrictions on access.
A central repository of datasets from the United Kingdom.
Survey data about the demographics, attitudes, and behaviors of Americans. Time-series data back to 1972 is available for some questions.
Integrated Public Use Microdata Series. A project of the Minnesota Population Center at the University of Minnesota, this site distributes microdata sets from historical and current censuses of both the U.S. and foreign countries. These data sets have been harmonized, so items from one census can easily be compared to items on another census.
The most comprehensive catalog of data sets in the United States; also a good source for some international data.
Surveys on health and health care conducted in 75 developing countries from 1984 to the present. Both statistics and raw data sets are available. Some data sets are available in GIS formats.
Raw data from many historical public opinion polls, including several hundred state-level polls, Harris polls, and the Computer Assisted Panel Study.
Data sets from the Mexican Migration Project, Latin American Migration Project, American Fertility Surveys, National Longitudinal Survey of Freshmen, Texas Higher Education Opportunity Project, and more.
Distributes data from five of Pew's research centers: Pew Research Center for the People and the Press, Pew Internet and American Life Project, Pew Global Attitudes Project, and the Pew Research Center Social and Demographic Trends studies.
1940s-present. Coded datasets of policy changes based on Congressional hearings, Congressional roll call votes, executive orders, State of the Union addresses, and more.
SDA allows online analysis of various datasets, including the General Social Survey, the American National Election Study, the U.S. Census Public Use Microdata Samples (PUMS), and a few others. This is a good option if you want a quick answer and don't want/need to download the entire dataset to get it.
Several thousand data sets on a variety of topics, including crime, demographics, the economy, education, employment, the environment, health, religion, social indicators, and more. Historical and longitudinal data is also available. Much of the data was collected in the United Kingdom, although some international data sets are available. Registration is required; this registration is free for academic users.