County and City Data Book
Including statistics for all U.S. counties, cities of 25,000 or more population, and places with more than 2,500 inhabitants. Useful for both business and school projects. Population, housing, business, and labor force data are featured.

Statistical Abstract of the United States
Statistics describing social, economic, political, and geographic changes in the United States.

United States Census
The ten-year census required by law provides massive amounts of population, housing, economic, and geographic data. The economic census, as well as other kinds of statistical data, also is found here.