I just finished reading Alan Ehrenhalt’s The Great Inversion, about the mass gentrification of American inner cities over the last generation or so. It’s got a lot of interesting tidbits, including – as an aside – an incredible pessimism about Philadelphia that I would love to be able to examine with either someone who knows the city better than I do, or a visit there myself, or better yet both. 

As far as Contributions to the Discipline go, my favorite is probably how the book navigates in an elegant and eminently sensible way past the dumb Atlantic Cities v. New Geography debate over whether cities or suburbs are “winning the future.” Ehrenhalt concedes that there is no “mass migration” towards the city center – that, for the moment at least, the balance of population in pretty much every metropolitan area continues to move farther and farther from traditional downtowns. But he points out that there is, undeniably, a “demographic inversion”: the professional classes are moving to inner city neighborhoods that, 30 years ago, were either slums or totally uninhabited, and suburbs are seeing faster growth in traditionally “urban” populations of immigrants and low-income people. Neither of these points is exactly breaking news, but it’s still refreshing to see it laid out with a clarity that the partisans on both sides tend to muddle.

But I finished the book wondering whether “inversions” and “migrations” are, in fact, as independent of each other as Ehrenhalt implies. Think about the many-decade-long period when overall population and wealth were both headed in the same direction, i.e., to the suburbs. There were many reasons to want to move out of the city in, say, 1960: preferential mortgage treatments, more space, less crime, better schools. (Also, if you were white, fewer black people. Not a good reason to want to move, but an influential one.) By the 1970s and 80s, as commercial and office functions started decentralizing wildly, you could add convenience to shopping and work to that list as well. And, of course, the suburbs had cache: that’s where you went if you were a successful, mainstream adult, especially with a family.

But look at that list: with the exception of space, none of suburbia’s benefits are inherent to a particular style of development or geographic location. Suburbs had better schools, safer streets, and better access to retail and jobs because that’s where the middle and professional classes lived. As the Great Inversion proceeds, those class-based amenities are going to shift to a greater and greater extent to central cities. In many cases, it’s already happened: the North Side of Chicago and Manhattan, two of the most intensely urban areas in the country, aren’t too far from Toronto-level crime levels. For the first time in history, San Jose is recording more homicides than San Francisco. Companies who want to attract young workers are moving their offices back downtown. Retailers and restaurateurs are moving to gentrifying neighborhoods. Elementary schools in Chicago, New York and elsewhere are being colonized – there really is no other word – by middle-class families, whose children are bringing up test scores dramatically.* Since pretty much no one sees the tide of inner-city gentrification turning back, these trends are only going to become more and more pronounced.

All of which changes the math for a generic American household – one that, like the vast majority of households, is unswayed by romantic notions of “urban authenticity,” or “hipness,” or whatever – considerably. If the prosaic quality-of-life measures by which most people decide where to live are a wash between any number of suburbs and the central city, and maybe even tilted towards the city in some places, you would expect to see many, many more people begin choosing to live in the city.

In other words, it seems like the logic of demographic inversion leads, eventually, to mass migration, as the broader part of the population chases the amenities that the wealthy have accumulated in their corner of the metropolis.

I can think of two obvious roadblocks to this process: space and housing costs.

As to space: There will, of course, be a good number of people who prefer a larger house to a smaller condo, who want their kids to have a yard, and for whom, as a result, living in the country’s densest neighborhoods is out of the question. But even on this count, the suburban advantage is much less pronounced than one might think. The vast majority of American cities have plenty of single-family-home neighborhoods in close proximity to downtown. Most American inner cities never looked like Manhattan, or even Brooklyn. Space may have been an issue, but it wasn’t like middle-class people in mid-century Kansas City or Cleveland or Dallas were fleeing airless tenements. The issue was crime; it was schools; it was economic and racial status.

Housing costs seem to me like a much more serious problem. Unlike low-density suburbs, where even within a “favored quarter” there can be plenty of room to continue building housing supply within reasonable driving distance of existing malls and job centers, American central cities tend not to have an enormous amount of easily-buildable vacant land, and also tend to have ferocious controls on densification of existing neighborhoods. In other words, once a neighborhood becomes desirable, demand can very quickly outpace supply and make it unaffordable to a large range of people. Now we’re in Ryan Avent’s “Gated City” territory, where the spoils of America’s mass affluence are hoarded by those who can afford to live in the wealthy central city, and everyone else has to contend with inferior schools, retail choices, and higher crime.

So even in the event of mass demand for living in central cities, it’s not clear that American cities are prepared to construct the housing necessary to accommodate a major increase in inner-city populations, and, as a byproduct, make living in the inner city affordable to a broad swath of Americans. We’re certainly a long way from facing that problem in most neighborhoods in most cities. But people who would cheer a mass migration back from the suburbs for reasons economic, environmental, social, whatever, should be looking to the places where it already exists – New York, Boston, Chicago, San Francisco – and trying to figure out how to fix it.

* This reminds me of something an urban planner friend told me recently. The common belief that the middle class won’t return to cities until the schools improve, he said, gets it exactly backwards. The schools will be the last part of the neighborhood to improve. The middle class will move in, tempted by proximity to jobs, shopping and restaurants; many won’t want to give those things up after they have children; and so, sooner or later, a critical mass of them will send their children to public schools, whereupon the schools will become “better.” We forget, he pointed out, that despite all the talk about teacher quality, charter schools, and new curricula, by far the greatest influence on a school’s test scores is the economic profile of its students. Urban schools are now “bad” because they are overwhelmingly made up of poor students. They will stop being “bad” when that is no longer the case.