Just some short thoughts for now, perhaps more soon if time permits.
The Census Bureau released its 2016 county population estimates late last week, and the numbers show a reversion to the trends of the 1990s and early 2000s: Sunbelt suburbs are growing faster than legacy cities. Blame land use policies if you like (I sure will) but those are the facts.
If cities are not growing as fast as once thought, though, it hasn’t been to the benefit of rural areas. Small counties were disproportionately represented among counties that lost population. The table below shows the number of counties gaining or losing population by county size.
Of the 37 counties that had a 3% or greater population loss, 27 had population under 10,000 and 36 had population under 50,000. The only sizeable county to lose 3% or greater was San Juan County, NM, which lost -3.05% of its 2015 population of 118,701 and has lost over 11% of its population since 2010. It is the only county of over 100,000 people to lose anywhere near that much; the next closest was Cambria County, PA, which lost 6%.
Further, of the 456 counties that lost over 1% of their population, 424 had population of 50,000 or less. Only 3 had population over 200,000 (St Louis city, Baltimore city, & Muscogee County GA). Of the 45 counties with population of 1,000,000 or more, only 6 lost population: Cuyahoga OH (Cleveland), Wayne MI (Detroit), Cook IL (Chicago), Suffolk NY (Long Island), Allegheny PA (Pittsburgh), and St Louis MO (St Louis suburbs). Six had population growth over 2% (Mecklenberg NC, Travix TX, Hillsborough FL, Clark NV, Orange FL, and Wake NC).
In short, the census estimates reflect long-standing trends of rapid growth in the Sunbelt and stagnation in the Rust Belt.
It’s a little unfair to compare small counties and very large counties, because it’s easier to have a large percentage swing in a small county. For example, Los Angeles County has over 10 million people, and there are probably some communities of 10,000 therein that shrank. The graph below avoids this problem by showing the distribution of counties gaining and losing population for counties up to 500,000 people. As we can see, the distribution skews towards the negative side for counties with population under 50,000 and toward the positive side for counties with population above 50,000.
For counties with over 1,000,000 people, the fastest growing counties are all in the Sunbelt, dominated by places like NC, FL, TX, and NV. Perhaps the most impressive county was Maricopa AZ (Phoenix) which grew by almost 2% and over 80,000 people. The fastest growing was Wake NC with 2.43%.
In California, the fastest growing big county (population over 250,000) was Placer, in the Sacramento suburbs, with 1.64%. Unlike many counties, growth in Riverside County actually picked up last year, with 35,000 people or 1.48%. Riverside was also the only big county in California to have a large positive contribution from domestic migration. The negative domestic migration from California counties is shocking: more domestic migrants (75,168) left LA County than the two largest domestic migrant gaining counties combined – not coincidentally, Maricopa County with 43,189 and Clark County NV with 27,735.
There will surely be many takes on the meaning of this census data, but the simple take here is that this is just a triumph of people doing what they’re allowed to do. A lot of economic growth in the US is in the Sunbelt, so people are moving there, and they’re moving to suburbs because that’s what you’re allowed to build. As for why growth is in the Sunbelt, that’s a more complicated question. The structural reasons for the decline of rural counties and the continued stagnation of Rust Belt cities are beyond the means of this blog.
However, given California’s high and still-rising cost of housing, our story isn’t very complicated: the economy is pretty good and lots of people want to live here, but we don’t build enough housing to let them do it. High housing costs are hurting California, and the sooner we do something about it, the better.
Let's Go LA 
An interesting follow-on study would be to analyze this at a greater degree of granularity than metro area. I suspect that the narrative of “growth = sunbelt = low density, suburban expansion” might break down – at least somewhat.
Having lived here in Wake County, NC for 17 years, I can say that, while outward growth continues apace, there is more *inward* growth going on right now than there ever has been and it seems to be accelerating. When I graduated college in 2005 and got a job, I wanted to live in downtown Raleigh, but there were literally ZERO options for modern apartments within walking distance of downtown. Now there are dozens of them, with thousands of residents.
Eleven years ago, an urban lifestyle was basically not available in this region. I chose to give that up in order to stay closer to home and also due to the opportunities afforded by the economic growth here. Many others I know, went to urban centers up north in order to have a more urban lifestyle. That sort of internal migration was a pretty big component of the supposed northern urban resurgence, wasn’t it? Well, planners and real estate developers in the sunbelt have caught on to this trend, and Raleigh is now able to retain and attract at least some of the more cosmopolitan types who would previously have needed to go to New York or Chicago. Not saying that Raleigh is New York. It ain’t. But factors like these do have to be at play, don’t you think?
Is there any way to zoom in to the census tract level? Compare the density of the top gainers vs top losers. That might give a bit of insight.
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