Atlanta, the transportation hub of the South, is not having its best year. I-20 has now buckled, and I-85 is weeks away from being back in order after improperly stored polyethylene pipes caught fire, engulfing the highway in flames and collapsing a bridge. As yet another chorus of cries erupts, demanding expanded public transportation in Atlanta, it’s worth taking the time to look at the subject practically and understand the conditions on which such a system depends in order to be an efficient choice. It is important not just for Atlantans but for anyone concerned with good public policy to understand that urban development—like so many aspects of economics—is heavily influenced by the natural evolution of diverse processes that are nearly impossible for the would-be planner to foresee or to design without coming to blows with the plans of millions of individuals, each with plans of his own. Economists call this kind of activity “spontaneous order,” and it exists even in the histories of our most rigid, concrete urban centers.
The metro Atlanta area has a size of about 8,376 square miles with a population of 5,710,795. That makes for a population density of about 682 residents per square mile (rpsm). By contrast, the DC area has a size of about 5,672 sq mi and a population of about 6,097,684. That’s a density of 1,075 rpsm. New York: 20.2 million, 6,725 sq mi, 3004 rpsm. Boston: 4,628,910, 3,507 sq mi; 1,320 rpsm.
Population density is a huge factor in the viability of public transportation, and having a smaller and widely dispersed population doesn’t lend itself to anything resembling an efficient public transport system. On net, such a system would wind up being a benefit to some (but, even then, not all) people who already live inside the I-285 perimeter and a net loss to everyone else in the state who would subsidize their comfort. I’ve seen the absurd proposed map passed around on Facebook by a progressive urban planning group showing a rail system that goes all the way to Braselton, GA, and beyond. For those unfamiliar with the geography of North Georgia, much of that map consists of small towns that could not in the foreseeable future be large enough and generate sufficient traffic to sustain even once-daily traffic to and from the city of Atlanta. In standard progressive fashion, however, it dispenses with economic considerations and promises the world, only to leave voters stuck with the bill when it fails.
Beyond this, let me add that anyone who points to two highway infrastructure problems recently and compares them to an idealized version of public transport is guilty of an atrocious Nirvana fallacy—the error of comparing a realistic version of one plan to an idealized, perfect-world version of another. It is a con game often employed by progressives who point to the sometimes messy, unpredictable realities of capitalism and compare them to a textbook version of socialism in which everything goes perfectly to plan. The messy truth is that major metro systems around the country face consistent problems, from maintenance issues in DC to financial shortfalls in New York and persistently high commute costs in Boston. Based on some brief online research, it seems to me that not a single major metro rail system in America is able to generate enough ticket revenue to cover the costs of its system. And for reasons already discussed, Atlanta is even less adapted to such a model, suggesting that its shortfalls from an expansive metro system would be considerable.
Atlanta isn’t alone, though. Cities like Los Angeles that are spread out over huge swaths of land are similarly decried as not having adequate public transportation, but, for the same reasons, it simply isn’t feasible to have it otherwise. Both Atlanta and LA grew up in the early twentieth century in regions where land was cheap (which is still true in Atlanta if not in LA) and modern transportation was available. In light of these factors, early residents and developers chose a wider dispersal of developments than their earlier counterparts in crowded, northeastern port cities. In New York, Boston, etc, by contrast, land was scarcer and since they were settled in earlier periods people had to live closer together to enjoy the same gains from cooperation and exchange.
As much as progressives would like it to be, this isn’t a story of enlightened city-dwellers versus ignorant suburbanites who resist public transportation because they don’t know what’s good for them. It’s a rational response to what people do when land is cheap: they use more of it (aka the first fundamental law of demand). As a result of these different evolutions under different environments, different modes of transportation will be more or less viable. That doesn’t mean that all cities will look like Atlanta and LA in the future nor like NY, DC, and Boston; it means that there is a natural variety among them that is a result of their histories, and trying to make one work like the other is likely to result in significant costs. It means that, as inconvenient as it may be for the planner mentality, there is a natural heterogeneity to human development that makes it unsuitable for the one-size-fits-all model that public transportation advocates invoke when they treat having a light rail system as a mark of urban sophistication and hold up northeastern cities that have such systems as the standard. Atlanta isn’t New York, though; nor Boston, DC, Philadelphia, Los Angeles, Phoenix, Dallas, Minneapolis, Chicago, or anywhere else. And to say that each of those cities has its own history isn’t just sentimentalism; it’s a reminder that historical processes have led to certain patterns of development, certain evolutions, that present us with both different constraints than other cities face and different opportunities. The sooner we appreciate this, the sooner we can avoid a huge malinvestment.