Urban area
An
urban area is an area with an increased
density of human-created structures in comparison to the areas surrounding it. This term is at one end of the spectrum of
suburban and
rural areas. An urban area is more frequently called a
city or
town.
Urban areas are created and further developed by the process of
urbanization. Measuring the extent of an urbanized area helps in analyzing
population density and
urban sprawl, and in determining urban and rural populations.
Unlike an urban area, a
metropolitan area includes not only the urban area, but also
satellite cities plus intervening
rural land that is socio-economically connected to the urban core city, typically by
employment ties through
commuting, because it is the labor market. This makes metropolitan areas a less relevant statistic for determining per capita land usage and densities.
Definitions vary somewhat amongst different nations. The minimum density requirement is generally 400 persons per square kilometer. In Australia, urban areas are referred to as "urban centres" and are defined as population clusters of 1000 or more people, with a minimum density of 200 people per square kilometer [
1]. In
Japan urbanized areas are defined as contiguous areas of densely inhabited districts (DIDs) using
census enumeration districts as units with a density requirement of 4,000 people per square kilometer.
European countries define urbanized areas on the basis of urban-type
land use, not allowing any gaps of typically more than 200 meters, and use
satellite photos instead of census blocks to determine the boundaries of the urban area. In less developed countries, in addition to land use and density requirements, a requirement that a large majority of the population, typically 75%, is not engaged in agriculture and/or fishing is sometimes used.
Statistics New Zealand defines
New Zealand urban areas for statistical purposes as a settlement with a population of a thousand people or more.
In
France, urban areas are referred to as
unités urbaines which literally mean "urban units" in the
French language.
United States
In the
United States there are two categories of urban area. The term
urbanized area denotes an urban area of 50,000 or more. Urban areas under 50,000 are called
urban clusters. Urbanized areas were first delineated in the United States in the 1950 census, while urban clusters were added in the 2000 census. There are 1371
United States Urban Areas & Urban Clusters with more than 10,000 people.
The US Census Bureau defines an urban area as: "Core census block groups or blocks that have a population density of at least 1,000 people per square mile (386 per square kilometer) and surrounding census blocks that have an overall density of at least 500 people per square mile (193 per square kilometer)."
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Ranked list of New Zealand main urban areas*
Largest urban areas of the European Union*
Largest urban areas of the United States*
World Urban Areas All identified world urbanized areas 500,000+ and others: Population & Density. Author seeks advice on any that appear to be missing: wcox@demographia.com
*
United States Urbanized Areas All 452 urbanized areas from 2000 census: Population, Land Area & Density
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U.S. Census Bureau: Maps of urban areas*
U.S. Census Bureau: Maps of urban clusters*
U.S. Census Bureau: Census 2000 Urban and Rural Classification*
Geopolis research group at the University of Avignon, France for European urban areas
*
Gridded Population of the World - contains links to urban area definitions and maps for over 230 countries/territories
*
City Mayors - The World's Largest Urban Areas in 2006*
City Mayors - The World's Largest Urban Areas Projected for 2020
