Sprawl correlates with higher rates of obesity, traffic fatalities, ozone pollution, and lack of social capital.
Sprawl may not be a four-letter word, but to many people it might as well be. You can include in that group the researchers at Smart Growth America, the national nonprofit coalition that advocates for “smart” development in U.S. metro areas—i.e., cities and towns with neighborhoods where people can walk or bike or use mass transit to get things done, rather than driving everywhere.
Back in 2002, in an attempt to quantify the extent and effects of sprawl development, Smart Growth released a report called Measuring Sprawl and Its Impact. This week, the group has come out with a follow-up study that uses more and better datasets to rank U.S. metro areas in terms of sprawl. It also outlines the human and economic costs of sprawl development.
Measuring Sprawl 2014 [PDF] looks at 221 metropolitan areas and 994 counties around the country, giving them number grades (higher is better) on a “Sprawl Index” by using four factors: density; mix of uses; strength of “activity centers” and downtowns; and accessibility of the street network.
The top 10 “most compact” areas nationally, regardless of metro size, were:
- New York/White Plains/Wayne, New York/New Jersey
- San Francisco/San Mateo/Redwood City, California
- Atlantic City/Hammonton, New Jersey
- Santa Barbara/Santa Maria/Goleta, California
- Champaign/Urbana, Illinois
- Santa Cruz/Watsonville, California
- Trenton/Ewing, New Jersey
- Miami/Miami Beach/Kendall, Florida
- Springfield, Illinois
- Santa Ana/Anaheim/Irvine, California
Some of those places may not seem like obvious leaders in compactness, but scored particularly high on one or another of the index’s criteria. Santa Ana, for instance, ranked especially well on street accessibility.
The list of top (or bottom) “most sprawling” areas was dominated by places in the Southeast. In order from lowest scoring (worst) to highest, they were:
- Hickory/Lenoir/Morganton, North Carolina
- Atlanta/Sandy Springs/Marietta, Georgia
- Clarksville, Tennessee/Kentucky
- Prescott, Arizona
- Nashville-Davidson/Murfreesboro/Franklin, Tennessee
- Baton Rouge, Louisiana
- Riverside-San Bernardino/Ontario, California
- Greenville/Mauldin-Easley, South Carolina
- Augusta/Richmond County, Georgia
- Kingsport/Bristol/Bristol, Tennessee/Virginia
Among large metro areas, “The biggest success story is surprisingly Los Angeles,” says Reid Ewing, a University of Utah professor who was the lead researcher on the study. “Los Angeles has actually densified substantially.” The famously car-dependent California city ranked seventh among metro areas with populations over one million. The report attributes some of L.A.'s high score to development around transit stations and an ordinance that allows developers to build denser projects in exchange for affordable housing.
Among smaller cities, Madison, Wisconsin, stands out, leading the group with populations between 500,000 and 1 million. The researchers attributed some of its success to concrete policy tools such as homebuyer assistance programs that encourage investment in existing buildings in the city’s core and a focus on downtown development.
Why is it better to find your city at the top of the rankings, rather than at the bottom – where Atlanta, Baton Rouge, Louisiana, and Hickory, North Carolina, rank as most sprawling among their respective cohorts? The researchers found that sprawl correlated with higher rates of obesity, traffic fatalities, ozone pollution, lack of social capital, vehicle miles traveled, physical activity, and residential energy use.
The researchers also found that residents of more compact metros had greater upward economic mobility: “for every 10 percent increase in an index score, there is a 4.1 percent increase in the probability that a child born to a family in the bottom quintile of the national income distribution reaches the top quintile of the national income distribution by age 30.”
Residents of more sprawling regions were stuck with fewer transportation options and higher combined costs of housing and transportation, despite higher housing costs in more compact cities. An average household in the San Francisco metro area (a national leader in terms of density, with a score of 194.1) spends 46.7 percent of its budget on combined housing and transportation. In Tampa, Florida, which scores a dismal 98.5, that proportion is 56 percent.
Residents of compact metro areas also have longer, healthier lives, with lower BMIs, lower blood pressure, lower rates of diabetes, and fewer car crash fatalities. An average American in a more compact county has a life expectancy three years longer than one in a less compact county.
All these are observations of correlation, not causation. But they tell a remarkably consistent story. Not only can cities limit sprawl through the use of specific policy tools, but the benefits for their citizens of doing so are real and life-changing.