An urban growth boundary, or UGB, is a regional boundary, set in an attempt to control urban sprawl by mandating that the area inside the boundary be used for higher density urban development and the area outside be used for lower density development.
An urban growth boundary circumscribes an entire urbanized area and is used by local governments as a guide to zoning and land use decisions. If the area affected by the boundary includes multiple jurisdictions a special urban planning agency may be created by the state or regional government to manage the boundary. In a rural context, the terms town boundary, village curtilage or village envelope may be used to apply the same constraining principles. Some jurisdictions refer to the area within an urban growth boundary as an urban growth area, or UGA. While the names are different, the concept is the same. Another term used is urban service area.
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Urban growth boundaries have come under an increasing amount of scrutiny in the past 10 years as housing prices have substantially risen, especially on the West Coast of the U.S.[1] By limiting the supply of developable land, critics argue, UGBs increase the price of existing developable and already-developed land. As a result, they theorize, housing on that land becomes more expensive. In Portland, Oregon, for example, the housing boom of the previous four years drove the growth-management authority to substantially increase the UGB in 2004. While some point to affordability for this action, in reality it was in response to Oregon State law.[2] By law, Metro, the regional government, is required to maintain a 20-year supply of land within the boundary. Even with the addition of several thousand acres (several km²) housing prices continued to rise at record-matching paces. Supporters of UGBs point out that Portland's housing market is still more affordable than other West Coast cities, and housing prices have increased across the country.
Albania maintains the 'yellow line' system hailing from its Socialist Regime - limiting urban development beyond a designated boundary for all municipalities.
The U.S. states of Oregon, Washington and Tennessee require cities to establish urban growth boundaries. California requires each county to have a Local Agency Formation Commission, which sets urban growth boundaries for each city and town in the county. However, in states such as Tennessee the boundaries are not used to control growth but rather to define long-term city boundaries. States such as Texas use the delineation of Extra Territorial Jurisdictional boundaries to map out future city growth with the idea of minimizing competitive annexations rather than controlling growth. Notable U.S. cities which have adopted UGBs include Portland, Oregon; Boulder, Colorado; Virginia Beach, Virginia; Lexington, Kentucky; and San Jose, California. Urban growth boundaries also exist in Miami-Dade County, Florida and the Twin Cities of Minnesota. Portland, Oregon is required to have an urban growth boundary which contains at least 20,000 acres (81 km2) of vacant land. Additionally, Oregon restricts the development of farmland. The regulations are controversial, but an economic analysis concluded that farmland appreciated similarly to the other land.[3]
In Canada, Vancouver, Toronto, Ottawa (the "Greenbelt") and Waterloo, Ontario have boundaries to restrict growth and preserve greenspace. They are notably absent from cities such as Calgary, Edmonton, and Winnipeg that lie on flat plains and have expanded outwardly on former agricultural land.
Controls to constrain the area of urban development existed in London as early as the 16th century. In the middle of the 20th century the countryside abutting the London conurbation was protected by the Metropolitan Green Belt. Further green belts were then created around other urban areas in the United Kingdom.
After the release of Melbourne 2030 in 2001, the state government legislated growth boundaries to limit urban sprawl. Since then, the urban growth boundary has been significantly increased a number of times and a further extension is currently proposed.
An Integrated Development Plan is required in terms of Chapter 5 of the national Municipal Systems Act No 32 of 2000 for all local authorities in South Africa. This plan would as one of it components include a Spatial Development Framework plan which would normally, certainly for the larger metropolitan areas, indicate an Urban Edge beyond which urban type development would be severely limited or restricted. The concept was introduced in the 1970s by the Natal Town and Regional Planning Commission of the Province of Natal (now known as KwaZulu-Natal) in the regional guide plans for Durban and Pietermaritzburg. The concept was at that stage termed an Urban Fence.[4]