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GEO-3: GLOBAL ENVIRONMENT OUTLOOK  
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Urban sprawl

Urban sprawl is defined as low-density, automobiledependent residential development (Dowling 2000). It is equated with intrusion into rural or undeveloped land on the periphery of a city or town, beyond the edge of service and employment areas (Chen 2000). Sprawling sub-divisions in post-war North America have been fuelled by economic expansion and encouraged by incentives for home ownership, singleuse zoning, government subsidies, and investments in highways and suburban infrastructure (ULI 1999, Sierra Club 2000a). As tax-paying, middle-income families left urban centres, many cities turned into impoverished city cores surrounded by car-dependent suburbs serviced by malls.

Private and public transport use (passenger-km/year per capita): Canada and United States

The per capita use of private vehicles in urban areas has grown in both the United States and Canada while the use of public transport has stagnated or dwindled

Sources: compiled from EC 1998, Wendell Cox 2000 and United Nations Population Division 2001

In the United States, a cycle of public transit decline, increased car use and longer commuting distances took place over the 1970s and 1980s; this was mirrored by Canada during the 1990s. Between 1981 and 1991, the number of car-kilometres travelled by Canadian and US citizens grew by 23 and 33.7 per cent respectively (EC 1998, Raad and Kenworthy 1998). The trend of increased urban car use and stagnant or declining transit use is illustrated on the left.

Encouraged during the 1990s by new road building and low fuel prices, the US suburban population grew by 11.9 per cent between 1990 and 1998, compared with 4.7 per cent for central cities (Pope 1999, Baker 2000, HUD 2000). Today, one-half of US sprawl appears to be related to population increase and the other half to land-use and consumption choices that increase the amount of urban land occupied per resident (Kolankiewicz and Beck 2001).

Suburban developments have been built over vast areas of North America's forests, wetlands, recreational wilderness and agricultural land. As these landscape features are lost, so are the services they provide, such as wildlife habitat, flood and run-off control, and soil productivity (Parfrey 1999). Between 1982 and 1992, an average of 5 670 km2 a year of prime farmland in the United States was developed for urban use (NRCS 2000). Today, an average of 9 320 km2 of land is being converted annually, with a substantial portion for suburban homes on lots of 0.5 ha (HUD 2000). In Canada, the urban areas occupying land that could be used for crop production increased from about 9 000 km2 in 1971 to 14 000 km2 in 1996 (Statistics Canada 2000).

Urban sprawl has environmental, social and economic consequences including traffic congestion, deteriorating inner cities that are often fragmented along class and racial lines, and suburban problems of isolation and lack of sense of community (Raad and Kenworthy 1998, Dowling 2000). Canadian cities are much less affected by sprawl than their US counterparts (Parfrey 1999, Baker 2000, Sierra Club 2000b).

Increasingly, state and local governments are implementing smart growth and sustainable development plans (see box below). Studies show that where urban density is highest, car use per capita is the lowest (Raad and Kenworthy 1998). Successful 'infill' projects in which decaying properties or vacant lots are developed to help cities rebound are now more common. On the other hand, in many places it is still less expensive in the short term for developers to buy and build on land outside city zones (Chen 2000) .

Compact urban development and smart growth

Over the past 10 years, a 'smart growth' movement has emerged in North America to combat urban sprawl. Smart growth is characterized by a mix of residential, office and retail land uses close to civic buildings clustered in a town centre. 'Smart' growth is emphasized rather than 'no' growth, and reform codes and ordinances are sought that permit smart growth characteristics and that create urban growth boundaries (ULI 1999). Smart growth is promoted by a broad coalition including environmental NGOs, social justice activists, local government officials, urban planners and affordable housing advocates. The movement promotes high-density neighbourhoods that reduce car use.

Compact development techniques advocated by smart growth and sustainable city initiatives include building within an already urbanized area, redeveloping on cleaned-up contaminated sites or 'brownfields', and cluster development on reduced-size lots. Such developments use less land area and help reduce travel distances, encourage walking and cycling, stimulate public transit, preserve open green spaces, wildlife habitat and farmland, and reduce impervious surface areas thereby improving drainage and water quality (US EPA 2001).

At the federal level, initiatives to help address sprawl-related problems include the US 1998 Transportation Equity Act (TEA-21) and the Livable Communities Programme. Most activity addressing urban sprawl takes place at the planning level of government, however. Many of Canada's major urban regions are instituting long-range transportation plans aimed at reducing car dependency and adopting sustainability strategies for higher density, mixed use urban development (Raad and Kenworthy 1998).

There are still many hurdles on the path to sustainable cities: powers to address urban sprawl are generally split among federal, state/province and local governments, and their proper roles are still undefined (Stoel Jr 1999, Dowling 2000); effective compliance regimes to ensure implementation are lacking (Raad and Kenworthy 1998); to some, smart growth implies the loss of individual freedom and property rights fueling an anti-smart growth lobby (Stoel Jr 1999); vested interests of the car manufacturing industry are strong, while suburban sprawl is so entrenched in the North American landscape and psyche that reversing the trend is a formidable challenge.