A great resource that provides access to a multitude of U.S. statistics is the Statistical Abstract of the United States, which is a compendium of statistics from a variety of government agencies. The most current edition is available in the Reference section of the IUS Library (HA202 .A3 1950). Older editions are available online (1878-2011) and in Reference (1950-present)
Also check out the relatively new Data.gov, which is a catalog of datasets from government agencies.