I've written recently about Glaeser and Resseger's research showing that workers in skilled cities tend to become more productive as their cities grow while workers in unskilled cities do not. I've also written about Abel et al.'s paper showing that while workers in all cities tend to become more productive as their cities grow denser, workers in skilled cities are especially likely to benefit. The latter receive, on average, three times the productivity gains of workers in the least skilled cities. Growth and densification are good if yours is a highly skilled city.
But the Glaeser and Abel papers also raise another possibility: perhaps skilled cities are better off keeping out the unskilled than growing without bound.
This is arguably an implication of their work. (And one I don't like, by the way.) Both Glaeser and Abel define highly skilled cities to be those with high percentages of college-educated workers. The higher the ratio of B.A.s to high school grads, the more skilled the city under their definition -- and the more the workers benefit as the city grows.
One way to keep a high ratio of skilled to unskilled is to price out the unskilled. The most effective way to price unskilled workers out of a city is to keep the cost of housing high. And, indeed, the highly-skilled cities on the coasts are adept at (and notorious for) using rigid land-use regulations to inflate home prices. (Or were until recently; more on that later.) The incumbent homeowners in these cities of course benefit from a tight housing supply since it raises the value of their properties. But perhaps their skilled workers benefit too.
I speculated about this last October without the benefit of Glaeser ir Abel's research:
Perhaps the elites in the superstar cities sense it is better to surround themselves with a uniformly high-quality workforce. They want to spend their time with other elites; letting in lots of less-skilled workers would introduce so much static, just as if Harvard were to throw open its doors to anyone with a half-decent high school transcript. In other words, an influx of less-skilled workers might dilute the experience for the high-skilled.
I got my undergraduate degree from Ole Miss and my law degree from Yale. I studied harder at Ole Miss, took harder classes and spent a lot more time with my professors. I thought law school was mostly boring and had a suburban home and the premium cable channels by my third year. But I probably got a better education at Yale than Ole Miss merely by hanging around a bunch of people who were smarter than me. There were economists, physicians, mathematicians, political scientists, a Broadway actor, an Olympic miler and, of course, a bunch of smart new college graduates from all over the country (but mostly from the Ivy League, Standford and Berkeley.). It was a small class of 175. It was impossible not to keep up with new ideas or trends because someone you bumped into would know about them. I wasn't paying a gazillion dollars for the law school classes, I was paying for the spillovers. It was a fair price.
The housing markets in LA, San Francisco and New York function as giant sorting machines. By setting home prices so high, they weed out all but the most skilled -- except for the class of relatively unskilled who are supported by price controls or subsidies. They're using the Ivy League model.
So are they better off? Yes, clearly, if they can shunt the less skilled elsewhere and continue to grow and densify. But it's hard to do both. High prices, in fact, require that the housing supply be kept tight in order for prices to stay high. Otherwise, the new supply of housing would drop home prices and the riff-raff (from their perspective) would come flooding back in. But perhaps merely increasing the density of skilled workers will yield the productivity gains yielded by growth and densification. Their motto could be, "We get smarter, not bigger."
I think this is probably wrong, though. What matters is being close to other people with the same skill set; that's where the knowledge and productivity spills occur. A software developer benefits from having a lot of other smart software developers around; a musician benefits from having a lot of other good musicians around. Adding more software developers or musicians who aren't quite as skilled shouldn't dilute this benefit because we city-dwellers largely control whom we interact with. Firms, in fact, segregate themselves by quality all the time. Deepening the labor pool simply can't hurt. I think cities like San Francisco and New York would be even more productive if they loosened their growth restrictions and allowed in more people.
And even if were true that the San Francisco model can achieve greater productivity without growth, there's always the risk that its sorting machine might break. To wit, a housing market collapse. Skilled workers cash out what they can and move elsewhere. Lower home prices attract the less-skilled who had been priced out of the market. A political and regulatory climate makes the city less hospitable entrepreneurs, who benefit from cheap space and light regulation.
It will be interesting to see what happens to productivity in these wealthy, slow-growth cities as the recession wears on. My guess is that they will have to begin growing vigorously again if they want to recapture the productivity they had at the peak of the housing boom.
