Urban growth boundary
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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.
Urban Growth Boundary in the United States 
The nation's first urban growth boundary was set up in Oregon under then governor Tom McCall, as part of the statewide land-use planning program in Oregon in the early 1970s. Tom McCall and his allies convinced the Oregon Legislature in 1973 to adopt the nation's first set of statewide land use planning laws. McCall, with the help of a unique coalition of farmers and environmentalists, persuaded the Legislature that the state's natural beauty and easy access to nature would be lost in a rising tide of urban sprawl. The new goals and guidelines required every city and county in Oregon to have a long-range plan addressing future growth that meets both local and statewide goals. In short, state land-use goals require:
- setting urban growth boundaries
- using urban land wisely
- protecting natural resources
UGBs and housing prices 
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. 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. By law, Metro, the regional government, is required to maintain a 20-year supply of land within the boundary.[clarification needed] 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.
Places with urban growth boundaries 
Albania maintains the 'yellow line' system hailing from its Socialist Regime - limiting urban development beyond a designated boundary for all municipalities.
United States 
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; Honolulu, Hawaii; Virginia Beach, Virginia; Lexington, Kentucky; Seattle, Washington; 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, and economic analysis has concluded that farmland lying immediately outside of Portland's growth boundary is worth as much as ten times less than similar land located immediately on the other side.
New Zealand 
Over the past two decades, greater Auckland has been subject to a process of growth management facilitated through various strategic and legislative documents. An overarching objective has been to manage the growth of Auckland in a higher density, centres-based manner consistent with the Auckland Regional Growth Strategy. Effect is given to this strategy through a series of layers of control including the Local Government Amendment (Auckland) Act, the Regional Policy Statement and then via District Plans. A key outcome of this process was the establishment of a Metropolitan Urban Limit (“MUL”) or urban fence that dictated the nature and extent of urban activities that could occur within the MUL and hence also dictated the relative values of land within the MUL.
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.
United Kingdom 
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.
South Africa 
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.
Hong Kong 
In the plan of some new towns, green belts are included and growth cannot sprawl into or across the green belts. In addition a majority of new towns are surrounded by country parks.
See also 
- Green belt
- Land use planning
- Community separator
- Urban rural fringe
- Urban open space
- Urban sprawl
- Prime farmland
- City and County of Honolulu Department of Planning and Permitting Ewa Development Plan (August 1997)
- 8th Annual Demographia International Housing Affordability Survey: 2012 Demographia/Performance Urban Planning.
- Ref. Metropolitan Durban - Draft Guide Plan, Natal Town and Regional Planning Reports Volume 28, 1974.