I live in one of the faster-growing cities in one of the fastest-growing states in America. A common joke here in Florida is that the state bird is the crane. (Get it?) Needless to say, growth is a contentious and emotional subject around here. And growth control is a hot topic.

And rightly so. Rapid growth can be disorienting and detrimental to the existing residents of a place—traffic jams where they didn't used to occur, crowded schools and hospitals. It's not at all clear, despite conventional wisdom, that growth itself should be viewed as any sort of measure of success or prosperity. Plenty of growing places aren't thriving, and plenty of thriving places aren't growing. (A particularly salient point in Florida, where our population growth is largely driven by low-wage jobs.)

And as we at Strong Towns have pointed out from the beginning, plenty of growth looks more like a Ponzi scheme than like real, resilient wealth. Think spread-out, low-value development that fails to pay for itself, leaving the next generation on the hook for this generation's overbuilt infrastructure.

But there's one particular line of argument when it comes to managing growth that I simply can't get behind. It's the notion that whether or not to grow, or precisely how much to grow—how many people to let in—is something that a community should naturally get to decide through the political process. That they maybe even have an inalienable right to decide.

It's certainly not just a Florida preoccupation. "More than a million people in San Francisco? Did anyone ask you?" inquired a prominent Bay Area activist in a blog post a couple years ago. Growth-control advocates in Boulder, Colorado muse about "carrying capacity" and overpopulation. Here in Gulf-coast Florida, the preferred pejorative is "Browardization," after Broward County on the state's Atlantic coast—held up by growth-control partisans as a warning of our grim fate if we don't slow our population growth.

The approval of locally unpopular development proposals, to hear many here tell it, constitutes a betrayal of the public interest by our own elected officials. Slow-growth appeals are usually accompanied by calls for development to be orderly, predictable, and always, always the favored buzzword: "compatible" with surrounding neighborhoods. None of this sounds objectionable on paper. Who would be against compatibility?

And yet, here's why this doesn't always sit right with me.

The actual outcomes on the ground of successful growth-control advocacy are often not very pretty. Whether in Boulder, Austin, San Francisco, Seattle, or Sarasota, those who claim we can keep existing neighborhoods under glass; restrain the pace of growth to only that which makes us comfortable; and preserve affordability, economic opportunity, and quality of life, and do these difficult things all at the same time—well, these people are indulging an illusion.

A city is a complex system. It's made up of thousands or millions of people making billions or trillions of decisions, in endless, fractal feedback loops. The city is not a machine; it's more like an ecosystem. You can tinker with an ecosystem—but when you do, you're subject to the law of unintended consequences.

The Water Has To Go Somewhere

One such consequence, when it comes to growth-control policies, is that you may simply displace growth to another location—without actually lessening any of its disruptive effects. In the process, you may even prevent some people from living and/or working where they otherwise would have preferred to—and in doing so, prevent the market signals from functioning that would have otherwise told us what is a productive and desirable location.

Many growth critics seem to operate with a flawed mental model that, rather circularly, treats development itself as the cause of population growth. Let the builders build, and the city gets more crowded and the traffic gets worse. Don't let them build so much, and growth will slow down and traffic will thin out. Easy, right?

Instead, think of demand to live and work in a place like the water in a river. Building a dam across the river, or channelizing it, doesn't make the water go away. The water has to go somewhere. It might rush around the dam. It might overflow the dam, or pool behind it. But it'll go somewhere.

Marin County, California, just north of San Francisco, is perhaps the most famous poster child for this. Thanks to powerful environmental advocacy, especially in the 1960s and 1970s, much of the western half of the county has been preserved as protected open space, while the eastern half was developed in a largely car-oriented pattern dominated by single-family houses. Resistance to denser development in those east-Marin communities remains fierce.