Volume 17, No.4, Winter 1999

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

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
. St. Paul, MN: Metropolitan Council.
Sierra Club. 1998. The Dark Side of the American
. San Francisco: Sierra Club.
U.S. Census Bureau. 1990. Census Lookup. Current
Level: State. Available: venus.census.gov/cdrom/
—. 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/

Randal O’Toole is senior economist with the Thoreau Institute

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