Socio-demographic Data on the U.S. population.

American Community Survey (annual profiles of communities) Decennial Census of Population and Housing (look for "sample data") 2000 1990 1980 1970 1960 and earlier Current Population Survey (annual survey of selected population characteristics).

Population Counts only (limited demographic detail).

Decennial Census of Population and Housing (use the decennial year links above, look for "100%" Data") Population Estimates (population counts for inter-censual years)

For assistance with selecting from among these sources or using them, contact eds@columbia.edu.