LibGuides: Census Data: Historic and Microdata

Historic Census Data

The Census Bureau does not provide data that's more than a few decades old on its website; use the sources below. Questions on surveys, subject categories, and census geographies change over time. Statistical census geography is revised every ten years, while legal geography is updated on an on-going basis. Nominal data is reported the same way that it was originally published. Normalized data has been modified so that data from the past has been transformed to fit present day boundaries.

The modern decennial census included at least two forms up to and including the year 2000: a short form collected basic data from 100% of the population, and a long form captured more detailed characteristics from a large sample. Beginning in 2010 the decennial census consisted of just a short form, while the long form was supplanted by the American Community Survey that was launched in 2005. Bear this in mind when making recent historical comparisons.

All of the IPUMS sites listed on this page are part of the IPUMS Project at the Population Center at the University of Minnesota. You must create one account to access these resources, but it's free for academic, educational, or non-profit research purposes.

IPUMS NHGIS
The National Historic GIS is the primary source for historical, public summary census data. Nominal data is provided for many datasets going back to 1790, and there is a selection of normalized data that goes back to 1990. The NHGIS also provides historic GIS boundary files.
LTDB
The Longitudinal Tract Database is part of the Diversity and Disparities project at Brown University. It consists of series of crosswalk tables for normalizing data at the census tract level from 1970 to 2010. The project also also provides a set of normalized data that covers this time period.

Social Explorer This link opens in a new window
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This interactive census web-mapping database makes it easy to create maps of nominal data going back to 1790. You can also download a subset of the historical summary data. Available to the Brown University Community.
Social Explorer helps visual analysis and understanding of the demography of the U.S. through the use of interactive maps and data reports. Primary functions include Demographic Data Analysis, Interactive Map/Report Design and Software Development. The main goal is to visually display the demographic change that has occurred in the U.S. since 1790 through the-present, for the country over all down to the level of the county. For more recent years, users can display areas as small as a neighborhood. Certain cities may even be displayed as far back as 1910. Toward this end, Social Explorer contains a collection of interactive demographic maps that can be viewed, queried and manipulated on the site.

Decennial Census Publications
The Census Bureau provides PDF copies of historic census reports. These can be useful for finding unique tabulations, and in some cases data that is not captured in digital data files.
IPUMS Complete Count Data
After 72 years the original, individual responses to census forms are publicly released. The IPUMS project has compiled person-level microdata from the 1790 to 1940 census that is anonymous (names and addresses removed) for social science and historical research.
National Archives Census Records
The National Archives preserves the original census ledgers and forms that include names, addresses, and written responses. The 1940 census is available in PDF; some but not all earlier records can be searched.

Ancestry Library This link opens in a new window
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The Ancestry library from Proquest captures historical records from the census and many other sources. Available to the Brown University Community.
With more than 1.5 billion names in over 4,000 databases, Ancestry Library includes records from the United States Census; military records; court, land and probate records; vital and church records; directories; passenger lists and more!

What the Census Calls Us
An interactive chart illustrating changes to racial and ethnic categories over time; an important consideration when making historical comparisons. Created by the Pew Research Center.

Microdata

While public summary data is aggregated into subject categories and geography, public microdata consists of anonymized sample records that represent individual responses to questionnaires. Special weighting variables are used to generate estimates from the samples, including cross-tabulations that are not created for the public summary datasets. To protect confidentiality, estimates can only be generated for large geographies like states, the largest metro areas, and Public Use Microdata Areas (PUMAs) that consist of 100k people. Sometimes it's possible to generate data for the largest counties.

Visit the Census Bureau's website and do a search through the various programs (decennial census, ACS, CPS) to find information about microdata for each program and to download raw data files for entire years and series.. The sources listed below are alternatives that allow you to create specific extracts.

Microdata Access
The Census Bureau's new tool for accessing recent PUMS data from the ACS and CPS, to create both extracts and estimates.
IPUMS USA
Public Use Microdata Samples from the decennial census (1850 to present) and the American Community Survey (2000 to present). Anonymous samples of records from these series (full count data is available for series where confidentiality has expired - see history section above).
IPUMS CPS
All of the individual, anonymized records for the monthly Current Population Survey from 1962 to the present. This is a longitudinal survey of 60k households (households are consecutively in the survey for 4 months, out for 8 months, back in for 4 months).
IPUMS ODAS
This tool allows you to generate estimates from the Annual Social and Economic Supplement (part of the CPS) online, without having to download an extract.