This polygon shapefile displays the Public Use Microdata Areas (PUMAs) for California. These data have been clipped to the shoreline for cartographic representation. A public use microdata area (PUMA) is a decennial census area for which the U.S. Census Bureau provides 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 PUMS files for these PUMAs contain a 5-percent sample of the long-form records. Since 1960, data users have been using these files to create their own statistical tabulations and data summaries. For Census 2000, state, District of Columbia, and Puerto Rico participants, following U.S. Census Bureau criteria, delineated two types of PUMAs within their states or statistically equivalent entity. PUMAs of one type comprise areas that contain at least 100,000 people. The other type of PUMAs, super-PUMAs, comprise areas of at least 400,000 people. The sample size is 1-percent for the PUMS files for super-PUMAs. 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. The UA Census 2000 TIGER/Line files contain a Public Use Microdata Area File, 2000 field containing the PUMA codes from the 5- percent sample. This layer is part of the Bay Area Metropolitan Transportation Commission (MTC) GIS Maps and Data collection. This dataset is intended for researchers, students, and policy makers for reference and mapping purposes, and may be used for basic applications such as viewing, querying, and map output production, or to provide a basemap to support graphical overlays and analysis with other spatial data. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.
