What exactly is the relationship between land use regulations and economic segregation? Previous research has shown that places with more restrictive land use regulations have higher housing costs and are more segregated by race, but now a new study from UCLA aims to give more detailed answers.

The paper, by Michael Lens and Paavo Monkkonen, differs from previous research on the subject in that it doesn’t use a proxy for land use regulations, like observed density or government fragmentation, or an index that sums all the many different components of these regulations. Instead, Lens and Monkkonen test many different kinds of regulation to get a better sense of the “specific pathways through which land use regulations affect income segregation.”

Credit: Robert Couse-Baker
Credit: Robert Couse-Baker


To briefly summarize their analysis, Lens and Monkkonen make four important findings.

  1. Density restrictions—think minimum lot sizes—are associated with more segregation of the rich, though not the poor;
  2. More difficult building approval processes are associated with segregation of the poor.
  3. More fragmented local governments are associated with high overall levels of segregation.
  4. Greater state-level involvement in land use planning is associated with lower overall levels of segregation..

For us, there are at least two big takeaways. Though the authors claim their findings cast doubt on the widely believed connection between low-density zoning and segregation of the poor—the classic “exclusionary zoning” problem—we think it suggests something else. After all, exclusionary zoning works by preventing the construction of housing that might be more affordable to middle- or low-income people, like smaller houses or apartment buildings. Whether that’s done up front by explicitly banning those types of buildings (ie, low-density zoning) or more surreptitiously through an arduous approval process, the result—and the mechanism of exclusion—is the same.

So the issue is less that low-density zoning doesn’t matter for the segregation of the poor, and more that there are many different regulatory tools local governments can employ to get to exclusionary land use. If the way communities block low-income-friendly development is by smothering it in red tape, rather than openly disallowing it, it’s important to understand the distinction to combat it—but equally important to understand that the end result is the same.

We’re also concerned that the author’s methodology doesn’t capture the either-or nature of exclusionary zoning—that is, a community can use either low-density zoning or an onerous approval process to keep out the kinds of housing it doesn’t want. Because cities with very onerous approval processes may feel they are sufficiently protected against the poor without low-density zoning, they may not use it. As a result, the researchers would see a weaker relationship between low-density zoning and segregation, even though a real relationship does exist.

Second, the findings about the effects of the scale at which decisions are made—more hyper-local decision-making associated with more segregation, and more state-level involvement associated with less—confirm once more the important role of politics and democratic structures in the extent to which land use laws become harmful.

Although they often seem to have only a local interest, housing and transportation policies affect entire metropolitan regions, and sometimes beyond. Though it may seem that only the people near a proposed rail station, for example, should have a large say about whether and how it gets built, that rail station also means access—or not—to the people, resources, and jobs in the neighborhood for residents in many other communities. Similarly, the decision of whether to build more housing—particularly lower-cost housing—concerns not just the people who live near the proposed construction site, but everyone who might want to move into such a home—again, especially when moving there would provide access to valuable resources like high-performing schools or jobs. The finding that state policies help minimize the segregating effects of some kinds of land use regulation suggests that broader geographic units can help overcome some of the prisoner’s dilemma problems that plague hyperlocal decision-making.

Finally, we should note that while the authors claim that these findings suggest the economic desegregation would most easily be accomplished by introducing low-income housing into high-income neighborhoods, rather than vice versa, that seems to be a separate issue not directly addressed by their valuable work here—something the authors acknowledged in an email exchange.

There’s a tendency, in land use policy as elsewhere, to view land use regulation through a simple lens: “regulation” is either good or bad. But the Lens/Monkkonen paper helps illustrate that “regulation” is not a single thing, but made up of many distinct parts that can be applied by many different institutions. Excessive restrictions on density clearly aggravate economic segregation, but the extent to which they do so is strongly influenced by the scale at which they’re determined.