Much of the current population data is derived from the Current Population Survey (CPS), which is a sample household survey of the noninstitutional civilian population in the United States. Its primary task is to produce monthly statistics on unemployment and the labor force, which are published by the U.S. Bureau of Labor Statistics in its monthly bulletin Employment and Earnings. For more information see Census.gov > Current Population Reports.
IPUMS is composed entirely of sample data, and some subpopulations may be too small to study with the sample data. Because the data are public-use, measures have been taken to assure confidentiality. Names and other identifying information are suppressed. Most importantly for many researchers, geographic information is limited.
The catalogs and indexes below may also be helpful: