Statistical information is an important part of many research projects and most libraries house a large assortment of resources. Perhaps the most useful single compilation is the Statistical Abstract of the United States, a small volume containing hundreds of tables relating to populations, social issues, economics as well as a wide variety of other numerical data.
The Gallup Poll, a widely recognized barometer of public opinion, publishes statistical survey results in annual volumes as well as in monthly magazines and the federal government collects an extraordinary amount of statistical data, much of which is released through the U.S. Census Bureau.
When more detailed information than that found in the Statistical Abstract of the United States is required, ask your reference librarian for more options. The U.S. Census of Population and Housing or USA Counties may be available. The National Trade Data Bank and the National Economic Social and Environmental Data Bank, two popular sources of economic information put out by the Commerce Department, may be available as well.