An urbanized area (UA) consists of densely settled territory that contains 50,000 or more people. The U.S. Census Bureau delineates UAs to provide a better separation of urban and rural territory, population, and housing in the vicinity of large places. At least 35,000 people in a UA must live in an area that is not part of a military reservation.

 For Census 2000, the UA criteria specify that the delineations be performed using a zero-based approach. Because of the more stringent density requirements and the less restrictive extended place criteria, some territory that was classified as urbanized for the 1990 census has been reclassified as rural. (Area that was part of a 1990 UA has not been automatically grandfathered into the 2000 UA.) In addition, some areas that were identified as UAs for the 1990 census have been reclassified as urban clusters.

 An urban cluster (UC) consists of densely settled territory that has at least 2,500 people but fewer than 50,000 people. (A UC can have 50,000 or more people if fewer than 35,000 people live in an area that is not part of a military reservation.) The U.S. Census Bureau introduced the UC for Census 2000 to provide a more consistent and accurate measure of the population concentration in and around places. UCs replace the provision in the 1990 and previous censuses that defined as urban only those places with 2,500 or more people located outside of urbanized areas.

 [source: Census Bureau geographic glossary, PDF format]
 
 

New urbanized areas based on Census 2000 are defined in the Federal Register notice dated May 1, 2002, available in PDF format. Corrections to the urbanized area definitions are included in a Federal Register notice dated August 23, 2002, available in PDF format.

 For more information on urbanized areas, visit the Census Bureau's urban/rural definitions web site at: www.census.gov/geo/www/ua/ua_2k.html

 The new urbanized area boundaries are included in the 2001 version of the TIGER/Line files, released May 2002.

 Paper on How You Can Evaluate PROPOSED Urbanized Area Criteria for your Metro Area, 10/19/01 (HTML format)