Meltzer, R. & Schuetz, J. (2010). What drives the diffusion of inclusionary zoning?Journal of Policy Analysis and Management, 29(3), 578-602.

Social scientists offer competing theories on what explains the policymaking process. These typically include economic rationalism, political competition or power struggles, and policy imitation of the kind that diffuses across spatially prox- imate neighbors. In this paper, we examine the factors that have influenced a recent local policy trend in California: inclusionary zoning (IZ). IZ programs require developers to make a certain percentage of the units within their market-rate resi- dential developments affordable to low- or moderate-income households. By 2007, 68 percent of jurisdictions in the San Francisco Bay Area had adopted some type of IZ policy. We test the relative importance of economic, political, and spatial fac- tors in explaining the rapid diffusion of IZ, across 100 cities and towns in the Bay Area. Consistent with an economic efficiency argument, results of hazard models provide some evidence that IZ is adopted in places with less affordable housing. However, political factors, such as partisan affiliation and the strength of afford- able housing nonprofits, are even more robust predictors of whether or not a local government adopts IZ. There is no evidence of spatial diffusion in the case of IZ adoption; jurisdictions are not, on average, responding to the behavior of their neighbors.

This manuscript is a nice exemplar for students interested in mixed methods. They have a set of hazards models that predict the adoption of inclusionary zoning, and they supplement those models with a very short case study of San Jose to illustrate some of their key points. I generally do not like shortie case studies, but this is nicely done and is offered for illustration; the authors do not overstate what the case means or shows.

So one of the key factors is having an affordability problem, which is good as we don’t need to be passing rules and policies places don’t need. Important to the passage of IZ are well-established housing nonprofits. The authors note that these nonprofits create an advocacy base for IZ and provide a group of stakeholders poised to engage in IZ implementation. But the fact that the nonprofits are well-established suggests that time matters: it takes time for people to recognize social problems, it takes time for nonprofits to form and become well-established, and it takes time to get things passed. Places where affordability problems have not been around awhile would have none of the above.

One of the things I wonder about concerns the IZ output. This study is just looking at whether local governments pass IZ rules. What would be interesting is the nature of those rules, and whether places in California–the location of the study–have passed IZ rules pre-emptively. That is, the state of California technically has a inclusionary housing rule–like it has a bunch of other rules it doesn’t always enforce but some times does. I had been thinking about IZ rules as the outcome of a strategic game where local council members in jurisdictions that have a problem with housing affordability pass some moderate attempt at IZ to preempt their nonprofits from bringing the state in, which would undermine local control. The result may more paper ordinances that do less than they otherwise would.