Geography Reference
In-Depth Information
The center of an American city (Central Business District or CBD) is identifiable
by the concentration of office tower blocks visible on the skyline, rather than by the
concentration of its population. This rule has only a very few exceptions. The four
main transactional metropolises of the US are New York on the Atlantic coast,
Chicago on the Great Lakes, and the California rivals, San Francisco and Los
Angeles, on the Pacific coast. These cities are characterized by extensive and
complex urban areas, as well as unusually high urban density in central areas. Urban
sprawl is active here, but these four cities differ from other US cities because of the
existence of densely populated neighborhoods in their centers. A record
440 inhabitants/hectare can be found in a portion of East Side Manhattan in New
York - a density comparable to that of eastern Paris. Otherwise, the maximum
density is less than 300 inhabitants/hectare for Chicago, 170 for San Francisco, and
about 120 for Los Angeles. In comparison, the average density of central Paris is
250 inhabitants/hectare. Apart from these major cities, the 100 inhabitants/hectare
mark is only reached in a few other metropolitan areas of the Megalopolis region:
Philadelphia, Washington and Boston.
City centers have been emptied of their population since the end of the Second
World War. Many US city centers have no neighborhood where residential density
reaches 50 inhabitants/hectare. Among the bigger ones, Detroit has a density of 45
inhabitants/hectare, St. Louis: 43, Denver: 40, Pittsburgh: 38, Phoenix: 36, Portland:
33, Atlanta: 26, and Tampa-St. Petersburg: 22. As for Houston, Minneapolis-St.
Paul, and Seattle, they barely exceed the threshold of 50 inhabitants/hectare.
Urban-planning programs between 1945 and 1973 ripped through entire
neighborhoods in order to make the CBD accessible by a network of penetrating
highways. Huge parking lots replaced warehouses and abandoned factories. At the
same time, many metropolises abandoned their tram systems. These urban renewal
programs (slum clearance) only received their first criticism in the 1960s [JAC 61].
From the 1970s, urban ideologies gradually reversed, going back towards a more
compact city as part of a postmodernist movement (school of Los Angeles). This
movement was transformed into real urban policy in the 1980s (Congress for New
Urbanism). Urban renewal operations were launched here and there, taking
advantage of opportunities left by industrial wasteland, or the retreat of port
activities (waterfront) away from the city center (brownfield redevelopment).
Impoverished, despite slum clearance policies, city centers attempted to attract
wealthy populations (Yuppies
3
). But the exodus of families from inner cities
3
. Term created from the acronym YUP for Young Urban Professionals, a class of young
workers in high-tech industries, media, and finance, with a high level of education and high
wages, often single, who are looking for apartments (condominiums) rather than houses and
are anxious to enjoy the cultural amenities and bustle of city centers.
