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Census Research Guide

Guide to locating statistical data as well as population schedules for a variety of U.S. Censuses. Also has links to information on censuses taken in a variety of other countries.

U.S. Census Chronology


Census of Population schedules (a line-by-line listing of each person living in the U.S. with personal information) available in microform in the Media Center (only for Iowa counties). Refer to Individual Households tab for further details.

1940 is available online at


Summary data is available in print Census, online PDFs, and extracted in several online databases (Social Explorer, ICPSR, Statistical Abstracts of the US)


Public-Use Microdata Samples (PUMS) were published. Some are available at ISU - use Quick Search to locate them. Also available online via IPUMS. Click on USA or International - then click on FAQ to see a basic explanation of what they are and what time period each of them covers.


Census of American Business was first administered. In 1935, the name was changed to the Census of Business which, in 1967, became the Economic Census. Online data is available for 2003-present via


Census blocks became available with the first Census of Housing. (Block groups have an average of 39 blocks per group.) The "Long Form" was first used in 1940.


Standard definitions for metropolitan areas are established.


Tract maps first became available, but only for metropolitan areas. Use Quick Search to locate them at ISU. The Census Bureau also provides a page of information on locating 1990 & 2000 tracts.


County Business Patterns first published.


The 1990 census was the first census where tract maps were made available for the entire U.S. In the late 1990's, Congress and the Census Bureau decided to drop the Long Form and replace it with the American Community Survey. American Community Survey was tested out in 2000-2002 and fully implemented in 2005.


Census 2010 data is only used for reapportionment. The American Community Survey collects all the socioeconomic data.

Your Librarian

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Lorrie Pellack
Head, Research & Instruction Services Dept.
150c Parks Library
Ames, IA 50011-2140
Phone: 515-294-5569