Although there are many definitions of sprawl, a central component of most definitions and of most people's understanding of sprawl is this:

Sprawl is the spreading out of a city and its suburbs over more and more rural land at the periphery of an urban area. This involves the conversion of open space (rural land) into built-up, developed land over time.

From the standpoint of urban planning institutions, the style of that conversion can sometimes be more important than the amount of the conversion. Organizations whose chief concerns involve urban planning goals may tend to emphasize qualitative attributes of sprawl -- such as attractiveness, pedestrian-friendliness and compactness.

But for those who are most concerned about the effect of sprawl on the natural environment and agricultural resources, the more important overall measure of sprawl is the actual amount of land that has been urbanized. Knowing the actual square miles of urban expansion (sprawl) provides a key indicator of the threat to the natural environment, to the nation's agricultural productivity and to the quality of life of people who live in cities and in the small towns and farms that are near cities.

Both the urban planning and environmentalist approaches to sprawl are valid ones for achieving sometimes differing -- although not necessarily competing -- goals.

Sprawl City adopts the environmentalist emphasis. It uses the term "sprawl" to refer to the reduction of rural land due to the increase of the total size of the land area of a city and its suburbs over a particular period of time.

That definition of sprawl is certainly not the only one. But it is unequalled as a standard quantitative measure of rural urbanization in cities in all regions of the country. Sprawl City uses this definition because it is based on the unrivaled measurements of Urbanized Areas by the U.S. Bureau of Census. No other source so methodically and with such standardization measures the loss of rural land to urbanization.

This measurement by amount closely resembles the most common American understanding of sprawl. For example, if an Urbanized Area covered 10 square miles in 1980 and covered 12 square miles in 1990, it would be common to say that the city and its suburbs over that period of time "sprawled 2 square miles."

If 25 square miles of open spaces around a city are urbanized, most Americans would consider that to be 25 square miles of sprawl, regardless of whether it was developed tastefully or not. They might be more offended by the sprawl if it included ugly development than if it was 25 square miles of well-planned sprawl, but the amount of sprawl - and the number of rural acres lost - would be the same. Thus, using this measure, it is possible to have well-planned sprawl or chaotic sprawl, to have high-density or low-density sprawl, to have auto-dependent or mass-transit-oriented sprawl. But regardless of the quality of the sprawl, the amount of sprawl is measured by the square miles of rural land eliminated by urban development.

None of that is to say that the quality of sprawl doesn't affect the amount of sprawl. Generally, well-planned sprawl will result in fewer square miles of rural land being covered by urban development. And environmentalists are interested in the urban planning aspects of anti-sprawl work because they can reduce the amount of energy used by and pollution produced by residents. And better planned sprawl is likely to keep its residents happier and less likely to decide later to move even farther beyond the urban center.

Clearly, though, the amount of rural land lost to sprawl is the key issue from an environmentalist and agricultural perspective. The amount of rural land loss and urban expansion also is significant to the quality of life of urban dwellers. The larger an urban area, the more difficult it will be for the average resident to reach the open spaces beyond the urban perimeter; the increase in urban distances can also affect commuting time, mobility and a resident's feeling of being "trapped."

[An Urbanized Area is a central city and its suburbs. For further explanation, click on the link on the main page.]