A Public Use Microdata Area (PUMA) is a decennial census area for which the Census Bureau provides specially selected extracts of raw data from a small sample of long-form census records that are screened to protect confidentiality. These extracts are referred to as "public use microdata sample (PUMS)" files. The 5-percent PUMAs comprise areas that contain at least 100,000 people. The 1-percent PUMAs, the Super PUMAs, comprise areas of at least 400,000 people. For Census 2000, PUMAs cannot be in more than one state or statistically equivalent entity. The larger 1-percent PUMAs are aggregations of the smaller 5-percent PUMAs.
Compared to other census products, such as the Redistricting Data File and Summary File 1 (SF 1) (based on 100 percent counts released at the census block level), or the Summary File 3 (SF 3) (based on the Census 2000 long form sample released at the census tract/block group level), the PUMS contains less geographic specificity, and a much smaller sample size.
For Census 2000, the Census Bureau offered the State Data Centers (SDCs) in each state, the District of Columbia, and Puerto Rico the opportunity to delineate PUMAs within their state or statistically equivalent entity using Census Bureau criteria and guidelines [PDF]. Two states, Florida and Rhode Island, declined to participate in this voluntary program and the Census Bureau delineated the PUMAs in those states.
For more information about the delineation of PUMAs contact: puma@geo.census.gov.
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