Tuesday, May 13, 2014

Despite the talk of urbanization, most large cities are becoming less dense (including SLC)

When comparing cities in terms of density, as we've done numerous times here, it's difficult to get an accurate picture of the typical density at which the average person lives in a particular city. Luckily the census bureau has a data set that uses a population weighted density, which helps solve this. Instead of just dividing a city's area by its population (which is the basic method), this alternative metric calculates a weighted average density across the census tracts that make up a city. We could think of it as calculating the population density at which the average person lives, which is handy. See this Richard Florida article for the data itself and further comments. While the average population density of the US in 2010 was 87.4 people/sq mi (using the old metric), the average person lived at a density of 5,369 people/sq mi, which is about the population density of Baltimore. Keep this in mind when you hear people (politicians especially) talking about small towns as being the "real America."

In order to check how this data compares with my preconceptions, I'll compare several notable (and local) Metropolitan Statistical Areas (MSAs) by this metric, first sorting by 2010 weighted density (in people/sq mi):

No surprise that NYC and San Francisco are at the top of this new metric, although who would of thought LA and Las Vegas were so dense? I was in these cities a few weeks ago, and they both always seem less dense than SLC. So much for perceptions. I suppose that LA shows one can have high density and still maintain a car culture (see the hilarious Curb Your Enthusiasm for more on LA culture). Also interesting is the fact that Houston and Phoenix are notably more dense than Minneapolis, which prides itself on its public transportation, bike culture, and urban living. Finally, note the surprisingly low density of St George and the fact that it was the one of the fastest growing MSAs in the nation the last several years. While I don't want to get sidetracked, the fact that people are moving to such low density cities in droves may be part of the cause of our lack of median wage growth the last couple of decades.

To see which MSAs are becoming more dense, we'll sort by change in weighted density from 2000 to 2010:

Again, it appears that overall people are moving to lower-density areas, as only five of these 19 MSAs (which house a large chunk of the country's population) became more dense from 2000-2010. Note that despite the talk of urbanization in many large cities today, only Portland, Seattle, and DC increased their average density over this period. Salt Lake City, sadly, did not. Anyone know what's been going on in Chicago since 2000 that's causing it to lose density much faster than any other large city?

Overall, this data is interesting, but hard to square with preconceptions (which means I'll have to rethink things). How is Las Vegas so dense when it seems so flat and spreadout?!

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