PUMS files have state-level Census 2000 data containing individual records of the characteristics for a 1 percent sample of people and housing units.

The PUMS files contain geographic units called super-Public Use Microdata Areas (super-PUMAs), a new geographic entity for Census 2000. The state files, which may contain one or more super-PUMAs, include geographic equivalency files that show the relationship between the super-PUMA and standard Census 2000 geographic concepts (e.g., counties, etc.). The super-PUMAs are made up of a Public Use Microdata Area (PUMA) or group of contiguous PUMAs (each PUMA must have a minimum of 100,000 population). PUMAs are only identified on the 5-percent files and not on the 1-percent files.