31 Flavors of Inclusionary Zoning: Comparing Policies From San Francisco, Washington, DC, and Suburban Boston

Problem: Over the past several decades, inclusionary zoning (IZ) has become an increasingly popular, but sometimes controversial, local means of producing affordable housing without direct public subsidy. The conversation about IZ has thus far largely ignored variations in the structure of IZ policies, although these variations can impact the amount of affordable housing produced and the effects of IZ on production and prices of market rate housing. Purpose: We provide a detailed comparison of the ways in which IZ programs have been structured in the San Francisco and Washington metropolitan areas and in suburban Boston. Methods: We create a unique dataset on IZ in these three regions by combining original data collected from several previous surveys. We use these data to compare the prevalence, structure, and affordable housing output of local IZ programs. Results and conclusions: In the San Francisco Bay Area, IZ programs tend to be mandatory and apply broadly across locations and structure types, while including cost offsets and alternatives to onsite construction. In the Washington, DC, area, most IZ programs are also mandatory, but have broader exemptions for small developments and low-density housing. IZ programs in the Boston suburbs exhibit the most heterogeneity. They are more likely to be voluntary and to apply only to a narrow range of developments, such as multifamily housing, or within certain zoning districts. The amount of affordable housing produced under IZ varies considerably, both within and across the regions. There is some evidence that IZ programs that grant density bonuses and exempt smaller projects produce more affordable housing. Takeaway for practice: Although variation in IZ program structures makes it hard to predict effectiveness, IZ's adaptability to local circumstances makes it a particularly attractive policy tool. IZ programs can easily be tailored to accommodate specific policy goals, housing market conditions, and residents' preferences, as well as variations in state or local regulatory and political environments. Research support: This article is adapted from a longer working paper written with financial support from the Center for Housing Policy, the research affiliate of the National Housing Conference.