Measuring Suburban Sprawl

Sprawl 5.jpg

Growth is good. Or so we've always been taught. But what if growth is poorly managed, so that it creates serious problems too? In an urban context, that's what we call sprawl.

Photo courtesy of USDA

Solving sprawl requires alignment of rules and incentives for land-development such that smart growth-management is the rule rather than the exception. Much has been written about this issue, from useful technical overviewsto inspiring examinations of good planning to soulful stories about neighborhoods left behind.

However, as the old management saw goes, “You can’t manage what you can’t measure.”  That’s why the Sierra Club ranked 30 regions in 1998 based on population and land-area growth, traffic congestion and losses of open space (full disclosure, this report was the first in a series produced in a campaign that I managed for the Club), and a few years later USA Today produced its own, more comprehensive index of sprawl based on population density and recent population density changes. And then, in 2002, Smart Growth America broke the mold with Measuring Sprawl and Its Impact, relying ons a larger number of data sets distilled into four factors:

  • Residential density;
  • Neighborhood mix of homes, jobs, and services;
  • Strength of activity centers and downtowns;
  • Accessibility of the street network.

I'm delighted that today the group unveiled a new sprawl index, authored by Reid Ewing (a co-author of the 2002 iteration). This new report also uses the four factors, however it relies on even more data as well as the 2010 rather than 2000 Census results. It also comes at a time when new evidence shows that metros – especially large metros – continue pulling jobs and people into their orbit, as opposed to small towns and the countryside.

The findings are mostly a series of rankings based on sprawl scores, and some patterns jump out at the reader. First, the south dominates the basement of the rankings. Atlanta is the nation’s most sprawling large metro overall and is one of 7 southern regions in the bottom 10. The same picture emerges with the bottom of the small metro ranking, with Hickory/Lenoir/Morgantown, NC as the most sprawling in that category. And the mid-sized metro ranking’s bottom 10 is filled entirely with southern regions. This doesn't surprise me since it lines up with regular state oil addiction reports NRDC used to produce, in which the burden of gasoline purchases on household budgets is invariably higher in Dixie.


Most sprawling medium metros, courtesy of Smart Growth America

It's a terrible problem for southern states, since sprawl is also statistically linked to negative average outcomes including less economic mobility, higher housing and transportation costs, fewer transportation options, shorter lives, higher obesity and blood pressure rates.

In contrast, California regions really shine in this report. 4 of 10 ranking at the top as “most compact and connected,” with San Francisco as #2 (no surprise that New York is still #1, same as 2002). Half of the top 10 large metros are in CA, and while there are fewer in the top 10 for small and mid-sized metros the state still makes an appearance.


Least sprawling large metros, courtesy of Smart Growth America

California policymakers deserve some credit for these findings. The state has leaped ahead of the nation with growth management in the past three decades. How so? Primarily by sharing more authority and funding with, and increasing accountability of, metropolitan planning organizations (MPOs), through a series of new state laws. In 1992, the state enhanced the last revolutionary federal transportation bill, 1991's Intermodal Surface Transportation Efficiency Act, by “suballocating” more federal transportation dollars to MPOs than any other state. And then in 1997, regions successfully secured project selection authority over 75% of state highway account spending. In 2006, Governor Schwarzenegger signed AB 32, the Global Warming Solutions Act, into law. This law mandates serious reductions in heat-trapping pollution, and the state has enacted other statutes to fill out the toolkit for achieving its goals. Most relevant here is the landmark Sustainable Communities and Climate Protection Act of 2008, or SB 375.

S.B. 375 pushes metropolitan planning and investment portfolios forward even further, requiring that regions develop Sustainable Communities Strategies which align the long-range transportation plan required of them by federal law with the state’s global warming pollution reduction goals. This has yielded an inspiring transformation in long-range plans, most notably in the cradle of sprawl, southern California, as my colleague Amanda Eaken writes.

Solving sprawl in California and other states requires measuring it first, and I commend Smart Growth America for accomplishing that again this year.