For the 2010 Census, the Census Bureau classified as urban all territory, population, and housing units located within urbanized areas (UAs) and urban clusters (UCs), both defined using the same criteria. The Census Bureau delineates UA and UC boundaries that represent densely developed territory, encompassing residential, commercial, and other nonresidential urban land uses. In general, this territory consists of areas of high population density and urban land use resulting in a representation of the "urban footprint." Rural consists of all territory, population, and housing units located outside UAs and UCs.
For the 2010 Census, the urban and rural classification was applied to the 50 states, the District of Columbia, Puerto Rico, American Samoa, Guam, the Commonwealth of the Northern Mariana Islands, and the U.S. Virgin Islands.
Urbanized Areas (UAs)—An urbanized area consists of densely developed territory that contains 50,000 or more people. The Census Bureau delineates UAs to provide a better separation of urban and rural territory, population, and housing in the vicinity of large places.
Urban Clusters (UCs)—An urban cluster consists of densely developed territory that has at least 2,500 people but fewer than 50,000 people. The Census Bureau first introduced the UC concept for Census 2000 to provide a more consistent and accurate measure of urban population, housing, and territory throughout the United States, Puerto Rico, and the Island Areas.
Urban Area Titles and Codes—The title of each UA and UC may contain up to three incorporated place or census designated place (CDP) names and will include the two-letter U.S. Postal Service abbreviation for each state or statistically equivalent entity into which the UA or UC extends. However, if the UA or UC does not contain an incorporated place or CDP, the urban area title will include the single name of a minor civil division or populated place recognized by the U.S. Geological Survey’s Geographic Names Information System.
Each UC and UA is assigned a five-digit numeric census code based on a national alphabetical sequence of all urban area names. A separate flag is included in data tabulation files to differentiate between UAs and UCs. In printed reports, this differentiation is included in the name.
Central Place—The 2010 Census urban areas will no longer include one or more designated central places. In preceding censuses, the central place included all incorporated or census designated places included in the urban area title, plus additional incorporated areas that met a population size criterion. The concept of central place for urban areas no longer is being applied.
Relationship to Other Geographic Entities—Geographic entities, such as metropolitan areas, counties, minor civil divisions, places, and census tracts, often contain both urban and rural territory, population, and housing units.