Urban sprawl is the term used to refer to the spreading of a city and its suburbs out from the centre over previously undeveloped rural land. The term is often used interchangeably with urbanisation. It tends to be characterised by the migration of populations away from high-density urban areas to low-density suburban areas.
The term is also used to refer to the social and environmental consequences, and so is often a highly politicised term, with many different theories as to what constitutes sprawl. While some urbanists measure the quantity of sprawl with the average number of residential units per acre, others focus on the decentralisation, others on segregation of uses, and so on.
In general terms, the pattern of urban sprawl tends to progressively follow these steps:
- During urbanisation, city centres experience higher density, with a rapid decline in periphery settlement.
- As economic growth continues, people with some wealth (i.e. the middle classes) begin to migrate towards the suburbs.
Urban sprawl tends to be viewed negatively and is often criticised for its consequences (see below). There are frequent calls for urban sprawl to be managed effectively to try and mitigate these consequences.
 Characteristics of urban sprawl
The following characteristics are often associated with urban sprawl:
 Single-use development
 Job sprawl
Patterns of employment spread out from the central business district (CBD) to the suburban periphery.
I.e. single family homes of large plots of land, spaced further apart with landscaping, roads, and so on, and is typically low-rise.
 Agricultural land converted to urban use
Fertile agricultural land surrounding cities is often converted to modern use.
 Housing subdivisions
Large areas of land comprised entirely of new-build developments, often characterised by curved roads and cul-de-sacs.
Cheaper land at the periphery often results in the proliferation of suburban lawns, country clubs and golf courses.
 Retail parks
Collections of commercial buildings (i.e. shopping centres) aimed at attracting consumers.
 Causes of urban sprawl
Urban sprawl can be caused by various different factors, and will often differ according to the specific country or region that is affected. However, some general causes can include:
- Lower land rates: Outer suburbs of cities are affordable comparative to city centres.
- Improved infrastructure: Increased expenditure on infrastructure that connects the peripheries to the centre better than previously.
- Rise in living standards: Increase in average incomes allow people to afford to commute longer distances.
- Lack of urban planning: Congestion, loss of trees and green space, inadequate infrastructure, and so on.
- Lower council tax rates: City centres often have high council tax rates compared to the periphery.
- Population growth: City grows beyond capacity due to a rise in population.
- Lifestyle choices: Those with higher levels of wealth choose to move somewhere with more space and lower density.
 Consequences of urban sprawl
Urban sprawl tends to attract a lot of criticism and opposition, particularly from environmental groups who see it as a tendency towards land and habitat loss, and a reduction in biodiversity.
The Garden city movement of the early-20th century provided some opposition to the trend, and new provisions were introduced in the Town and Country Planning Act 1947, such as the incorporation of green belts around urban centres.
Some of the typical consequences that give rise to urban sprawl opposition include:
 Public expenditure increase
Infrastructure and building developments often financed with public money.
 Traffic increase
With single-use developments being spaced apart, and further from the urban centre, people tend to rely more heavily on cars.
 Environmental issues
 Social issues
Urban sprawl can lead to the homogeneity of an area as people of the same income/social group, ethnicity, age, etc., move to the suburbs. One such trend is ‘white flight’, whereby white people moved out of city centres to the suburbs, leaving poorer black communities in the centres.
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