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PUMS Documentation

View the available subjects, detailed codes for variables, changes related to each release, an explanation of sample design, methodology, and accuracy, and files to determine if you are using weights correctly for the American Community Survey Public Use Microdata Sample (PUMS) files. These documents are organized by data year.

Supporting data for the documentation below is available on the Accessing PUMS Data page.

  • 2020
  • 2019
  • 2018
  • 2017
  • 2016
  • 2015
  • 2014
  • 2013
  • 2012
  • 2011
  • 2010
  • 2009
  • 2008
  • 2007
  • 2006
  • 2005

2020 ACS PUMS Estimates

2020 ACS 1-Year PUMS with Experimental Weights

The Census Bureau did not release its standard 2020 ACS 1-year Public Use Microdata Sample (PUMS) data because of the impacts of the COVID-19 pandemic. The PUMS data have been released with experimental weights and replicate weights and are available for the nation, regions, divisions, states, and Public Use Microdata Areas (PUMAs). Please visit the link below to be directed to the 2020 ACS 1-year PUMS with Experimental Weights. Here you can access the files as well as related technical documentation. The experimental PUMS files will not be released on

2016-2020 ACS 5-year PUMS

The Census Bureau released the 2016-2020 ACS 5-year PUMS files as part of its standard release for the ACS 5-year products after determining the resulting data were fit for public release.


Guidance for novice ACS PUMS files users.

PUMS Variable Changes and Explanations

Important information about 2020 geography and variable changes.

Subjects in the PUMS

A list of topics included in each of the housing and population record files

Code Lists

Detailed codes for variables that contain a large number of coded responses, such as ancestry and occupation.

PUMS Top Coded and Bottom Coded Values

List of variables with responses exceeding a state-specific value that are replaced with a predetermined value.

Accuracy of the PUMS

A basic explanation of the sample design, estimation methodology, and accuracy of the data.

PUMS Estimates for User Verification

Examples of PUMS estimates with their standard error and margin of error.

PUMS Record Counts

Counts of unweighted records for each PUMS file.

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