Urban sprawl

Urban sprawl or suburban sprawl mainly refers to the unrestricted growth in many urban areas of housing, commercial development, and roads over large expanses of land, with little concern for urban planning. In addition to describing a particular form of urbanization, the term also relates to the social and environmental consequences associated with this development. In Continental Europe the term 'peri-urbanisation' is often used to denote similar dynamics and phenomena, although the term urban sprawl is currently being used by the European Environment Agency. There is widespread disagreement about what constitutes sprawl and how to quantify it. For example, some commentators measure sprawl only with the average number of residential units per acre in a given area. But others associate it with decentralization (spread of population without a well-defined centre), discontinuity (leapfrog development, as defined below), segregation of uses, and so forth. The term urban sprawl is highly politicized, and almost always has negative connotations. It is criticized for causing environmental degradation, intensifying segregation and undermining the vitality of existing urban areas and attacked on aesthetic grounds. Due to the pejorative meaning of the term, few openly support urban sprawl as such. The term has become a rallying cry for managing urban growth. The term 'urban sprawl' was first used in an article in The Times in 1955 as a negative comment on the state of London's outskirts. Definitions of sprawl vary; researchers in the field acknowledge that the term lacks precision. Batty et al. defined sprawl as 'uncoordinated growth: the expansion of community without concern for its consequences, in short, unplanned, incremental urban growth which is often regarded unsustainable.' Bhatta et al. wrote in 2010 that despite a dispute over the precise definition of sprawl there is a 'general consensus that urban sprawl is characterized by unplanned and uneven pattern of growth, driven by multitude of processes and leading to inefficient resource utilization.' Reid Ewing has shown that sprawl has typically been characterized as urban developments exhibiting at least one of the following characteristics: low-density or single-use development, strip development, scattered development, and/or leapfrog development (areas of development interspersed with vacant land). He argued that a better way to identify sprawl was to use indicators rather than characteristics because this was a more flexible and less arbitrary method. He proposed using 'accessibility' and 'functional open space' as indicators. Ewing's approach has been criticized for assuming that sprawl is defined by negative characteristics. What constitutes sprawl may be considered a matter of degree and will always be somewhat subjective under many definitions of the term. Ewing has also argued that suburban development does not, per se constitute sprawl depending on the form it takes, although Gordon & Richardson have argued that the term is sometimes used synonymously with suburbanization in a pejorative way. Metropolitan Los Angeles for example, despite popular notions of being a sprawling city, is the densest metropolitan region in the US, being denser than the New York metropolitan area and the San Francisco Bay Area. Essentially, most of metropolitan Los Angeles is built at more uniform low to moderate density, leading to a much higher overall density for the entire region. This is in contrast to cities such as New York, San Francisco or Chicago which have extremely compact, high-density cores but are surrounded by large areas of extremely low density. The international cases of sprawl often draw into question the definition of the term and what conditions are necessary for urban growth to be considered sprawl. Metropolitan regions such Greater Mexico City, Delhi National Capital Region and Beijing, are often regarded as sprawling despite being relatively dense and mixed use. According to the National Resources Inventory (NRI), about 8,900 square kilometres (2.2 million acres) of land in the United States was developed between 1992 and 2002. Presently, the NRI classifies approximately 100,000 more square kilometres (40,000 square miles) (an area approximately the size of Kentucky) as developed than the Census Bureau classifies as urban. The difference in the NRI classification is that it includes rural development, which by definition cannot be considered to be 'urban' sprawl. Currently, according to the 2000 Census, approximately 2.6 percent of the U.S. land area is urban. Approximately 0.8 percent of the nation's land is in the 37 urbanized areas with more than 1,000,000 population. In 2002, these 37 urbanized areas supported around 40% of the total American population.