Sprawl City

Here is a city that, during the period of study, lost population but experienced profound sprawl. In light of that, how can population growth be considered an important factor in American sprawl?

In the fall of 1999, environmentalists had gathered in San Francisco to strategize against sprawl, and Richard Schneider was trying to add something to the agenda. A leader in the Bay Area Chapter of the Sierra Club, Schneider rose to complain that all the plans to combat sprawl were neglecting a key cause of sprawl - population growth.

But his concerns were dismissed with the cry of "What about Detroit?"

That basically stopped any more discussion of population growth at the meeting. Indeed, simply saying, "What about Detroit?" has been one of the most effective tactics around the country in keeping the population factor off the anti-sprawl agenda.

"What about Detroit?" refers to the fact that the Detroit Urbanized Area's population actually declined by 7% from 1970 to 1990, yet its land area grew by 28%. Indeed, what about Pittsburgh, Milwaukee, Cleveland, New York City, Buffalo, and Dayton? Each of these Urbanized Areas, and several others, also lost population between 1970 and 1990. And all but one had sprawl - lots of sprawl, in several cases.

Obviously, based on those examples, sprawl can be caused by something other than just population growth. In Detroit, 100% of the sprawl was caused by non-population factors. The entire cause of Detroit's sprawl was a complex of factors that lead to an increase in urban land consumption per person (in other words, that lead to declining density).

Any anti-sprawl campaign that ignores land use and consumption factors is doomed to failure - because stabilizing population is not by itself enough to stop sprawl.

The fact that Detroit's sprawl is unrelated to population growth sometimes is taken to mean that the sprawl of other cities is also unrelated to population growth. But it may simply mean that population growth is not the only factor in sprawl.

To understand what the Detroit model can teach us about sprawl, we must ask: Do Urbanized Areas with population growth experience sprawl in significantly higher amounts than Urbanized Areas with population decline? The answer from Census Bureau data on the 100 largest Urbanized Areas is a clear "yes." On average, the more population growth of an Urbanized Area, the worse the sprawl. While Detroit with its population decline sprawled by 28%, the 89 cities which HAD population growth experienced an average sprawl of 75%.

While the average city with NO population growth still sprawled by 26%, the cities which HAD population growth experienced a much higher average sprawl of 75%.

Those 89 cities with population growth sprawled by nearly three times as much as the 11 cities with population decline, which averaged 26% sprawl.

Detroit needs to hear about the population growth aspect of sprawl even though population growth may not be occurring in its area lest it become careless and adopt policies designed to increase its population.

Our literature search found that many anti-sprawl advocates and planners fail to make that comparison. Thus, they tend to draw the wrong conclusion about what cities like Detroit teach us.

They are correct in pointing to Detroit as an example that shows us that even when there is no population growth, there still tends to be a substantial "background rate" of sprawl brought about by many factors.

Census Bureau data on the 100 largest U.S. Urbanized Areas show that about half the sprawl in the country is related to land use and consumption factors that increase the amount of urban land per resident. In a few Urbanized Areas like Detroit those factors are related to all of the sprawl. Such facts are stark reminders that any anti-sprawl campaign that ignores land use and consumption factors is doomed to failure - because stabilizing population is not by itself enough to stop sprawl.

But Detroit does not prove that population growth is irrelevant to sprawl. Rather, it provides a comparison that proves the opposite. Yes, Detroit had extensive sprawl even though it lost population. If, however, Detroit's population had actually grown at the rate of the average Urbanized Area in America, the sprawl likely would have been far worse - based on the experience of the rest of the country. In comparison with the experience of other cities, Detroit had minor sprawl.

The citizens and decision-makers of Detroit need to hear about the population growth aspect of sprawl even though population growth may not be occurring in their area. Such education not only will help them understand why their sprawl problems are not as bad as the average city but also may keep them from becoming careless about adopting city policies designed to increase their population.

If Detroit's population had actually grown at the average U.S. rate, its sprawl likely would have been far worse.

So, what about Detroit? Well, because it had no population growth, it apparently had a lot less sprawl than most other cities.