My roommate and I were having a late-night chat about the desirability of zoning laws -- this happens more often than you'd expect -- and whether city density would increase or decrease if they were done away with. Both of us are generally in favor of higher density development, and both of us are generally skeptical of attempts to control land use. I happen to also believe that these two interests dovetail quite nicely: if you were to get use of restrictions on the use of land, the density of most cities and towns would increase, to the benefit of all.
But there's one very big problem with my belief. As my roommate noted, the real-world evidence just doesn't seem to bear it out. Cities with higher densities -- NYC, for instance -- tend to be very restrictively zoned and subject to massive land use regulation. On the other hand, cities without zoning -- think Houston -- aren't dense at all, sprawling out for miles and miles. In other words, at first glance, people seem to prefer to live in wide-ranging, low-density development.
Is my argument completely sunk?
I don't think so. I can't help but suspect that interpreters of the real-world evidence often get the causal relationship backwards: zoning doesn't create density, so much as density creates zoning.
That's because zoning, on the most basic level, is little more than the reflection of the land use preferences of a particular community. The larger and more cohesive that community becomes, the stronger its preferences. And the more people you pack into a town, square mile, or city block, the more likely it becomes that a few of them will attempt to enshrine their development priorities in law. Eventually the neighborhood's collective priorities will manifest themselves legally: not only are residents likely to petition for the creation and alteration of a neighborhood's zoning laws, there are also a bewildering number of ways that one or two concerned citizens can insert themselves in the process of administering the land use code.
In this conception, New York's huge number of zoning laws aren't the reason New York is dense and prosperous, but simply an indication of the large number of cohesive interest groups per square mile within its borders. In Houston and other sprawling cities, neighborhood groups are more dispersed, have fewer common interests, and generally are less likely to have significant legal leverage over the areas they inhabit.
If I'm right, this does illustrate how severely parochialism can undermine efforts to improve land use regulation. It's not deeply held principles that sabotage reform -- it's Neighbor Joe from Down the Street, who doesn't know the first thing about the large-scale economic effects of zoning but does think that a four-story apartment building would be an eyesore. That's not such a problem if Joe is by himself, but as you increase density, the number of Neighbor Joes multiply, meaning reformers are pushing against an ever-greater counterweight.