Krugman’s blog, 7/22/13

There were two posts yesterday.  The first was “Did Sprawl Kill Horatio Alger?”:

Honest truth: I wrote yesterday’s post suggesting that sprawl may have killed Detroit without knowing either about David Leonhart’s forthcoming article on how sprawl seems to hurt social mobility or the study on which it is based — a study, by the way, not yet available at David’s link, although the underlying data are there.

What Leonhart suggests, and apparently the still unavailable study also suggests, is that sprawling cities that put the poor far away from job opportunities tend to have low upward social mobility. I did a bit of data-crunching here. I took my favorite measure of sprawl, population-weighted density in thousands per square mile, versus the new study’s measure of upward mobility, the probability of children born in the bottom quintile making it into the top quintile; the data points are the top ten metro areas by population, not including New York, which is so much denser than anyone else that including it would scrunch everyone into the lower left corner:

Yep, there’s a pretty strong correlation, although not perfect. What’s the matter with Chicago?(And what’s not the matter with Houston?) And as Leonhart suggests, Atlanta is the real poster child here: massive sprawl and very low social mobility.

Is the relationship causal? You can easily think of reasons for spurious correlation: sprawl is associated with being in the sunbelt, with voting Republican, with having weak social safety net programs, etc.. Still, it’s striking.

And the William Julius Wilson “spatial mismatch” theory of urban ills is looking pretty good, isn’t it? (Actually, the emergence of “underclass” problems among low-opportunity whites points in the same direction).

Great stuff. Now, can I have the full study, please?

The second post of the day was “ATL v. BOS:”

Still playing around with sprawl and all that. As many people have pointed out over the years, the most obvious comparison among major US metro areas is between Boston, still relatively traditional in urban structure, and Atlanta, the Sultan of Sprawl; not long ago the cities were about the same population, although Atlanta is growing much faster. A comparison looks like this:

where the CO2 number comes from Glaeser and Kahn (pdf). In brief, incomes are lower in dollar terms in Atlanta, but people are moving there all the same for the cheap housing. This sounds like a win, but you can argue that it actually reduces national income. Also, the Atlanta model — with only about 1/4 Boston’s weighted population density — arguably leads to substantial external costs: more greenhouse gas emissions, in part because of slightly longer commutes, in part because of much lower use of public transit. And maybe lower social mobility, because sprawl leaves low-income workers stranded away from the jobs.

Of course, if you believe with George Will that the only reason liberals like public transit is because it diminishes individualism and makes us ripe for collectivism,and if you believe climate change is a gigantic hoax, and if you believe that social mobility is entirely about individual virtue as opposed to the economic environment, you won’t see this as problematic at all.



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