In addition to the historic Census files, 1790-1950, ICPSR archives and distributes Census data acquired from the United States Census Bureau as well as files prepared by ICPSR and other principal investigators for the decennial years 1960, 1970, 1980, 1990, and 2000. These include major sets such as the Summary Tape/Count Files, Master Enumeration District List (MEDList) files, and Public Use Microdata Samples (PUMS), as well as various subsets. ICPSR's holdings of 1960 Census data include Public Use Microdata Samples (PUMS) 1-in-100 and 1-in-1000 samples and Census tract-level data. Starting in 1960, the Census Bureau created the Public Use Microdata Samples (PUMS) as part of each decennial enumeration. The PUMS contain individual- and household-level information from the long-form questionnaires distributed to a sample of the population enumerated in the Census. The Public Use Microdata Samples make it possible for researchers to create tabulations tailored to their particular questions and to make time-series comparisons. Because of confidentiality reasons, the 1960 samples, as well as the 1970 samples, do not identify any places smaller than 250,000 inhabitants. The Census tract-level data provide aggregate data summarized at the level of the Census tract. Census tracts are statistical subdivisions, most of which are within Standard Metropolitan Statistical Areas (SMSAs). Tracts were originally designed to be relatively homogenous with respect to population characteristics, economic status, and living conditions.
For more information, visit the IPUMS USA Web site.