Compendium of U.S. economic, social, and political data. A good first stop when you're looking for statistics.
This portal from the National Consortium for the Study of Terrorism and Responses to Terrorism includes a Global Terrorism Database, datasets on terrorism, and an index of research on terrorism, counter terrorism, radicalization, and more.
Detailed data from individual and business tax filings. From the Statistics of Income Division of the IRS.
The United States Geological Survey’s (USGS) geospatial data and maps website. Access to geospatial datasets for hydrography, elevation, wetlands and many other natural and cultural features. For an interactive map for finding data see the National Map Viewer.
Data on U.S. commodity trade, including global trade patterns and state and metro-area export statistics.
Statistics on law enforcement, spending, and staffing of the federal law enforcement agencies (e.g. the FBI, IRS, and INS). From Syracuse University.
Information and statistics on presidential elections, past and present, from the National Archives and Record Administration.
Digital maps covering a variety of US Census demographic categories, plus GIS data in vector boundary files for spatial aggregations of tabular census data at all levels of the census hierarchy.
Current and historical temperature and precipitation data back to 1895 for selected cities, states, regions, and the nation.
Country-level data covering trade and investment. Includes data on exports and imports by commodity, foreign investments, balance of payments, etc.