Public Use Microdata Sample (PUMS)

The Census Bureau’s Public Use Microdata Sample (PUMS) files are a set of anonymized records from individual people or housing units, with disclosure protection enabled for respondent confidentiality. The Census Bureau produces 1-year and 5-year PUMS files with estimates based on a representative sample of the population: 1-year release (1%) and 5-year (5%). 

Only selected geographic areas are identified for the tabulation of PUMS data, including Region, Division, State, and Public Use Microdata Areas (PUMAs). PUMAs are statistical geographic areas defined for the dissemination of PUMS data and constituted of non-overlapping areas that partition each state into areas containing about 100,000 residents.

For more information on PUMAs, click here.

Estimates generated with PUMS microdata differ from American Community Survey (ACS) estimates in the following ways:

• PUMS files include only about two-thirds of the cases that were used to produce ACS estimates.
• PUMS data are not designed for statistical analysis of small geographic areas since PUMAs (100,000+ population sample size) are the most detailed geographic areas available for data analysis. 
• It is possible to create custom estimates and tables using PUMS data as opposed to using the pretabulated ACS tables and variables. However, PUMS data is more complex to use and constitutes a smaller sample size with no geographies smaller than PUMAs.
• PUMS files include additional edits to protect respondent privacy and modifications such as top-coding of continuous variables with outlying values and the reduction of category availability for certain data variables.

To read more about using PUMS data vs ACS data, click here.