Urban prairie is a term coined to characterize vacant city lots. Urban prairie results from widespread building demolition to facilitate urban renewal

Urban renewal

Urban renewal is a program of land redevelopment in areas of moderate to high density urban land use. Renewal has had both successes and failures. Its modern incarnation began in the late 19th century in developed nations and experienced an intense phase in the late 1940s – under the rubric of...

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Urban prairies can result from several factors. The value of the properties may fall too low to provide financial incentives for their owners to maintain aging buildings. It may have resulted from deurbanization

Deurbanization

Deurbanization or deurbanisation is the physical decline in the urban population as a result of economic or social change. Deurbanization is commonly defined differently from suburbanization because it describes a migration to rural previously uninhabited regions that had low population density,...

 or crime. Vacant properties are acquired by local government as response to unpaid property taxes and could be used for criminal activity, which tends to prompt demolition.

In flood-prone areas, government agencies may purchase developed lots and then demolish the structures to improve drainage during floods. Some neighborhoods near major industrial or environmental clean-up sites are acquired and leveled to create a buffer zone and minimize the risks associated with pollution or industrial accidents. Such areas may become nothing more than fields of overgrown vegetation, which then provide habitat

Habitat (ecology)

A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant or other type of organism...

 for wildlife.

Urban prairie is sometimes planned by the government or non-profit groups for community gardens and conservation

Conservation movement

The conservation movement, also known as nature conservation, is a political, environmental and a social movement that seeks to protect natural resources including animal, fungus and plant species as well as their habitat for the future....

, to restore or reintroduce a wildlife habitat, help the environment, and educate people about the prairie.