Finding, Acquiring, & Preparing Census Data

Ryan Clement

Data Services Librarian

February 2021

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  • Become familiar with four essential concepts for working with Census data
  • Locate various sources of Census data
  • Locate other complementary sources of large population data

A Brief Census History

Census in the Constitution

The actual Enumeration shall be made within three Years after the first Meeting of the Congress of the United States, and within every subsequent Term of ten Years, in such Manner as they shall by Law direct.

U.S. Const. art. I, § 2.

The Decennial Census


Door-to-door Census Enumerators

Electronic Access!

The Changing Census

What happens to Census data after 72 years?

Essential Census Concepts

  • Aggregate data vs. microdata
  • Census geographies
  • 100% data vs. sample data
  • Data definitions

100% Data

  • Short form census
  • Most precision
  • Fewest questions

Sample Data

  • Census long form (2000 and before)
  • American Community Survey
  • Most information
  • Make sure samples are comparable!

Census Geography


  • Most common
  • Tables of statistics
  • Determined by government needs
  • Smallest available geography: census "blocks"


  • More difficult to obtain, or work with
  • Not 100% complete
  • Allows innovative use 
  • Available at the individual respondent level

Data Definitions

Census Sources

print census records

Census Sources

historical data, microdata

Census Sources

historical data, easy access

Census Sources

quick access, current data

tidycensus in R

Complementary Data Sources

Wrap-up Question

What would you like to explore using Census data? What other datasets would you like to combine with Census data?


  • Most images courtesy United States Census Bureau except:
  • Census Geography image courtsey MIT Libraries
  • Government Documents image courtesy San Jose State University Libraries
  • All logos courtesy of the respective organization

Census Data for 2021 J-Term Data Science

By Ryan Clement

Census Data for 2021 J-Term Data Science

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