Sprawl and Obesity in Chicago: Why All the Fuss?
It has always been difficult to make something out of nothing, but a new report linking America’s growing obesity problem with urban sprawl (suburban living) sets a new record for political spin.
The report (Measuring the Health Effects of Sprawl), released by Smart Growth America and the Surface Transportation Policy Project, purports to demonstrate that people living in more sprawling, suburban counties are fatter than people who live in more dense central cities. Accepting, for the sake of discussion, the validity of the results (which I do not), the results fall far short of significant.
The Chicago area claims make my point. The researchers suggest that in less-sprawling counties, people walk more, which accounts for much of the doubtfully reported difference in weight. Using their formula, one can conclude that the average resident of less-sprawling Cook County walks approximately 20 minutes more per month (40 seconds per day) than residents in more sprawling Grundy County.
Even with their microscopic research tools, the authors find little by way of health effects. The average resident of Cook County--the most urban in the Chicago area--is estimated to weigh 0.9 pounds less than the slothful ne’er-do-wells who inhabit the North Shore communities of Lake County. But it is Grundy County residents who really stand out, weighing in at 0.5 pounds more (8 ounces).
The story is similar elsewhere around the nation. Boston-dominated Suffolk County residents can look down on their suburban neighbors, who weigh up to 1.7 pounds more. Or one can look at San Francisco, whose residents are a fit 2 pounds lighter than their counterparts in sprawling Marin County.
When is the last time you saw a late-night cable television commercial for a weight-loss program claiming it could take off two pounds in a lifetime?
So much for manipulating the inconsequential to feign significance. Centers for Disease Control data demonstrate that obesity has skyrocketed in the United States over the past 10 years. From 1991 to 2001, the obesity rate rose from 12.7 percent of the population to 20.5 percent in Illinois. By comparison, the report estimates the largest sprawl-related obesity difference among Chicago-area counties at 1.9 percentage points--one-quarter the Illinois increase over the past 10 years. Something else is going on.
Suburbanization and sprawl did not start in the 1990s. In fact, the 1990s were the least sprawling decade since World War II, with urban densities remaining largely unchanged. And transit’s share of urban travel is little more miserable today than it was 10 years ago. Car usage increased less in the 1990s than in any decade since before 1940. Yet obesity increased significantly over the past decade.
There are also potentially fatal flaws in the survey design. The researchers excluded the impact of household income in their calculations. Generally, obesity tends to fall as incomes rise. Income alone, had it been included, could have negated the results. And the “sprawl index” the researchers concocted for each county is so skewed by New York City data that the equation developed to predict results could have been rendered useless.
But one thing is sure. Measuring the Health Effects of Sprawl falls far short of establishing any material or believable nexus between sprawl and obesity. Public policy should not rest on differences of a pound or less.
Wendell Cox is a senior fellow of The Heartland Institute; a consultant to public and private public policy, planning and transportation organizations; and a visiting professor at a French national university. He was a three-term member of the Los Angeles County Transportation Commission and a member of the Amtrak Reform Council. His email address is email@example.com.
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