Driving and Density

One technique proposed for combating "urban sprawl" is increasing population densities. Government planners are beginning to require new residential developments to house more people per acre. Even existing low-density suburbs are supposed to be rebuilt to higher densities.

The "smart growth" plan for Portland, Oregon, considered a model for anti-sprawl policies, calls for increasing the density of the entire urban area, suburbs and all, from under 3,000 to nearly 5,000 people per square mile (Metro 1994). A report by Metro (1996, 20), Portland"s regional planning agency, says that "congestion signals positive urban development."

In reality, however, most people have always lived in fairly low densities. They don"t necessarily want to change that fact. Nor is increasing density likely to achieve the objectives of its proponents.

It was not until 1920 that the Census Bureau counted more Americans living in urban areas than in rural areas (U.S. Census Bureau 1995). And by that year, many city dwellers were already moving to low-density suburbs (which census takers count as urban rather than rural). In 1990, the Census Bureau found that nearly half of all Americans lived in the suburbs. Half the remainder lived in rural areas (U.S. Census Bureau 1993). In other words, only a quarter of the nation lives in what the Census Bureau calls "central cities."

A careful scrutiny of census data (U.S. Census Bureau 1993) shows that only a small percentage of Americans live in truly high densities:

Only about half of all Americans live in densities of 2,000 per square mile or higher. To put this in perspective, Indianapolis and Tulsa have densities around this figure. Half of all Americans live in cities that are this dense or more, while half live in even less crowded areas. About 28 percent live in rural areas, which have between zero and 200 people per square mile.

Only 3 percent of Americans live in densities like New York"s 20,000 people per square mile. (Manhattan"s density is 50,000 per square mile.)

Only about 18 percent of Americans live in cities with densities above 5,000 per square mile-cities such as Seattle, Washington, D.C., Chicago, and Boston. About a third live in densities of 3,000 or more (Houston and Atlanta have densities of about 3,000). In other words, two-thirds of all Americans live in cities with densities of 3,000 per square mile or less. Bozeman, Montana, has about 2,300 people per square mile, while Little Rock has 1,700; Colorado Springs, 1,500; Chattanooga, 1,300.

All these numbers count only the central cities. Suburbs around these cities are typically much lower.

Advocates of higher density say that it will improve urban livability. Because people will live more closely together, they will reduce auto usage, and more people will walk or ride transit (Sierra Club 1998).

But Census Bureau (1990) surveys (which asked one out of six households how they got to work) indicate that hopes for reducing auto usage are unrealistic. Ninety percent of commuters drive to work until densities are above 5,000 per square mile. Even above that density, huge changes in density are needed to significantly change driving behavior.

For example, quadrupling Seattle"s density from 5,000 per square mile to New York"s 20,000 might cut per capita driving in half. But with four times as many people, twice as much traffic would be on the roads.

It is not even likely that simply quadrupling density would lead Seattle to achieve New York"s low driving rates. Unlike Seattle, New York enjoys very high employment densities as well as a historically dense transit network . Most American cities have widely dispersed employment, with less than 10 percent of jobs located downtown. Mass transit is only efficient when employment densities are high.

"Smart growth" is even more impractical when applied to entire urban areas-meaning the central cities and their suburbs. Only three of the nation"s 400 urban areas have densities greater than 5,000 per square mile. For the rest, even doubling density would reduce per capita auto driving by only about 5 percent. Twice as many people, each driving 95 percent as much translates to a 90 percent increase in traffic. Since "smart growth" calls for few to no new roads, this means far more congestion.

Once we understand that the "smart growth" solutions will increase congestion, we can begin to understand their appeal to people who expect to benefit from more crowds. Transit agencies love density. The Metropolitan Council (1996, 54), which operates transit in Minnesota"s Twin Cities, says that "as traffic congestion builds, alternative travel modes will become more attractive."

Big city mayors and officials also love these policies, which will give them more control over the suburbs. Portland city councilor Charles Hales makes no bones about his dislike of the suburbs around his city. He has called the suburbs "trashy . . . godawful subdivisions" (quoted in Ehrenhalt 1997, 23). Officials and business executives tied to urban downtowns also like "smart growth." It would reduce the low-congestion advantage that suburban shopping and office centers have over downtowns.

Ironically, the push for congestion is at odds with worldwide trends toward lower densities. Today"s "smart-growth" policies echo those adopted by most European countries after World War II, when they decided to emphasize high-density housing and transit and heavily tax autos and gasoline. Yet today, European cities are losing population, their suburbs are growing rapidly, urban densities are falling, auto ownership and usage is rising, and transit usage is stagnant or declining (Kenworthy and Laube 1999).

"In worldwide perspective, rapid growth of automobiles began in the United States because we were richer than other nations," says University of California (Irvine) economist Charles Lave (1992, 11). "But other nations headed down the same path as their incomes increased." Lave concludes that "the desire for personal mobility seems to be unstoppable."

Policies to increase density will be an urban disaster. In the years ahead, they will have the opposite of the intended effect, leading to an even more rapid movement away from the cities.

Ehrenhalt, Alan. 1997. The Great Wall of Portland. Governing, May, 20Ð24.
Lave, Charles. 1992. Cars and Demographics. Access 1: 4Ð11.
Kenworthy, Jeffrey R., and Felix B. Laube. 1999. An International Sourcebook of Automobile Dependence in Cities, 1960-1990. Boulder, CO: University of Colorado Press.
Metro. 1994. Regional 2040 Recommended Alternative Technical Appendix. Portland, OR, September 15. ---. 1996. Regional Transportation Plan Update. Chapter 1. Portland, OR, March 22.
Metropolitan Council. 1996. Regional Transportation Plan. St. Paul, MN: Metropolitan Council.
Sierra Club. 1998. The Dark Side of the American Dream. San Francisco: Sierra Club.
U.S. Census Bureau. 1990. Census Lookup. Current Level: State. Available: venus.census.gov/cdrom/ lookup/CMD=LIST/DB=C90STF3A/ LEV=STATE.
---. 1993. Land Area, Population, and Density for Places: 1990. Available: www.census.gov/population/ www/censusdata/places.html. (March 23).
---. 1995. Urban and Rural Population: 1900 to 1990. October. Available: www.census.gov/ population/censusdata/urpop0090.txt.

Randal O'Toole is senior economist with the Thoreau Institute ([email protected]).

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