On the surface, sprawling subdivisions and commercial zones are economic boons to local businesses and municipalities. The construction of dwellings, stores, and infrastructure creates employment opportunities. Home owners and commercial ventures that move into the area often provide additional revenue to local governments in the form of property taxes and sales taxes. However, such development often produces drains on local environmental resources, shifts the economic burden of development to longtime residents, increases transportation and energy costs, and diminishes overall community character.
Environmental costs
One of the most obvious environmental effects of widespread building construction is the destruction of wildlife habitat. To make way for human dwellings and their associated infrastructure, natural land is plowed under, graded, and paved. Slow-moving streams are often channeled to provide more efficient drainage for housing tracts and commercial areas. Although small areas of wildlife habitat remain, they may be too small to support all the native species that lived there before or may be widely separated from one another. This arrangement often forces wildlife to cross dangerous human-dominated landscapes to find food or mates.
Exurban low-density neighbourhoods consume more energy per capita than their high-density counterparts closer to the city’s core. (An exurb is an affluent residential community located beyond the suburbs in a metropolitan area.) Energy for heating, cooking, cooling, lighting, and transportation is largely produced by burning fossil fuels (such as gasoline, home-heating oil, natural gas, and coal), a process that contributes to air pollution and global warming. To reach their jobs in the city or other employment areas, many suburban workers must commute by automobile. By the early 21st century the average to-work commute time for Americans was 26.9 minutes, and the bulk of this was done by automobile. In addition, trips to grocery stores or other retail establishments in the suburbs must also be done by automobile. Air pollution produced by gasoline-powered automobiles can combine with other pollutants from industry to form photochemical smog.
Modern suburban dwellings are typically larger than their counterparts in cities, requiring more energy to heat them in the winter and cool them in the summer. Single-family houses and stand-alone commercial structures can also leak winter heating and summer cooling through multiple exterior walls. In contrast, city apartments not only are typically smaller but also are better able to retain these resources: heating and cooling have greater difficulty escaping because many apartment walls, ceilings, and floors are often shared with neighbouring units.
Vast areas of impermeable surfaces in built-up areas often replace water-absorbing vegetation and permeable soils. Residential and commercial roofs, roads, and parking spaces for automobiles greatly impede the absorption of water into the soil. Rainwater and snowmelt run off these surfaces and may quickly pool in areas of low elevation, increasing the risk of local flooding. Chemicals present on pavement at the time of rain are often carried with runoff as water pollution, reducing water quality and threatening aquatic ecosystems downstream.
Economic costs
Although the phenomenon of urban sprawl contributes greatly to various sectors of the economies of developed countries, there are several economic costs. Many of those costs are passed on to longtime residents of the community or are borne by the public at large. In the United States, current residents of a city or town typically subsidize new construction and infrastructure even before new residents move in. A portion of the tax revenue normally spent on existing neighbourhoods is allocated to the new development. As a result, fewer resources are available to maintain services (such as fire and police protection and the repair of roads and utilities) in older neighbourhoods, and many cities and towns often raise taxes to compensate.
After residents move in, they must contend with high transportation costs associated with automobile ownership and endure time-consuming commutes. Surburban residents pay higher energy fees on average than city dwellers. In addition, since homes, stores, workplaces, and schools are dispersed, suburbs pay more for bus transportation for school-age children, road construction and maintenance, and materials used to build infrastructure, such as electrical wire and pipes needed for energy and water delivery.
Other economic costs are borne by the public at large. For example, new construction typically occurs on land formerly used for agriculture. As this land is converted to urban use, any new agricultural land must be created at the expense of natural areas (such as forests, wetlands, and grasslands). Free ecosystem services (such as flood control and water purification) and natural scenery are often lost or heavily degraded in the process of land conversion.
In newly developed urban areas, the practice of Euclidean zoning segregates housing types by size and income, separating wealthy residents from those in the middle and lower classes. Such economic stratification may also occur in older city neighbourhoods as wealthier residents move to newer housing tracts. A period of decay typically ensues: as the tax base erodes, much-needed repairs to roads and utilities are delayed or canceled.
Many authorities argue that urban sprawl diminishes the local character of the community. Ubiquitous retail chains with extravagant signage and façades are often the first to move into newly developed areas. Small local businesses are often hidden by the visual noise of larger stores and restaurants or are clustered into strip malls. Smaller stores and restaurants may not be able to outcompete larger businesses or may be forced to close from lost sales due to changes in automobile traffic patterns that favour larger businesses. While residents may be comforted by the presence of familiar establishments, there is often very little in town centres and commercial zones to distinguish one community from the next.