Putnam’s arguments (summarized at the end of Chapter 12) are threefold.
- “Sprawl takes time” and results in more time spent alone in a car and therefore less for civic engagement.
- “Sprawl is associated with increasing social segregation” and that segregation has led to less community participation.
- “Sprawl disrupts community ‘boundedness'” and that physical fragmentation reduces societal involvement.
Although Putnam’s claim—that sprawl erodes social capital—is widely referenced, my survey of the evidence makes me suspicious. My objections are threefold.
First, sprawl does not absorb more commuting time than does urbanization. Data from the National Household Transportation Survey shows astonishingly similar travel times across residential densities. Actually, residents of high densities spend the most time traveling. (Caveat: the NHTS is for “travel time” not specifically “commuting time,” which Putnam is interested in, though commuting only accounts for about 1/26/4 of all personal trips.)
In fairness, high density households spend about 1/3 less time driving and proportionately more time walking, busing, or biking. So it’s possible that urbanites use that extra 20 minutes per day to form social networks on public transit, but it seems equally possible that suburbanites form social networks while carpooling. In any case, no matter what the residential density, households sink roughly the same large chunk of time into commuting (74 to 79 minutes/day, most of which, even at high densities, is driving).
Putnam asserts a rough formula for measuring the effects of commuting: “each additional 10 minutes in daily commuting time cuts involvement in community affairs by 10 percent.” Still, I can’t see why sprawl is the culprit here. Instead, the culprit seems to be something like congestion, or perhaps the sheer physical size of cities (admittedly, related to sprawl), or perhaps even the population size of cities, which necessitates physical breadth. If sprawl is irrelevant here, it may help explain a point that Putnam apparently takes to be puzzling: that both surban and urban residents in big metro regions have less social capital than their small town counterparts.
Second, sprawl may be associated with social segregation, but the evidence that this erodes social capital is not conclusive, at least as far as I’m aware. Putnam does cite a couple of interesting studies here, but there are many more he bypasses. In a more comprehensive survey of the evidence,“The Effects of Sprawl on Neighborhood Social Ties,” Lance Freeman finds that “the existing evidence is not conclusive” and that moreover very high densities may actually be corrosive of social capital.
Freeman’s study goes on to find that residential density is unrelated to neighborhood social ties, but is strongly related to automobile dependence. As car dependence is generally a feature of sprawl, it may be that Freeman’s study supports Putnam’s conclusions. Still, both Freeman’s survey of the literature and his data analysis should serve as a cautionary tale for imputing too much explanatory power to low residential density, which is often treated as the defining characteristic of sprawl.
Third, the importance of community “boundedness” is, as far as I can tell, based on only one study that’s now more than 30 years old. Admittedly, it was something of a classic, but it’s rather hard to imagine that the same cultural and geographic forces in play in 1972 are the same ones that now impede social capital. For just one example, city center populations have been growing again, rather than hollowing out as they were in the 1970s.
I’d like to see more evidence on this subject. It could be that Putnam is basically right and I’m just nitpicking, but for the time being I’m suspending judgment on the social effects of sprawl.
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