Integrated Public Use Microdata Sample (IPUMS)
This project from the Minnesota Population Center aims to bring a consistent format and documentation to U.S. and international censuses as well as the U.S. Current Population Survey. It is "microdata" so it has information on individuals and households. It consists of three parts: IPUMS Microdata Series International, IPUMS Microdata Series USA, and Microdata Series CPS (Current Population Survey). The first contains census microdata from around the world and the second has microdata from every U.S.Census since 1850. The final has data from since 1962 and is consistent with their U.S. census data.