June 6, 2023
For more than a century, local governments throughout the United States have used zoning to shape future growth. Through rules that regulate what sorts of housing can be built where, localities may either allow for new development or restrict construction to maintain the status quo. Using a first-of-its-kind database of zoning laws across an entire state, we provide evidence that strict zoning regulations limiting construction to single-family homes are associated with inadequate access to affordable housing and with the segregation of people by income, race, and ethnicity.We leverage the Connecticut Zoning Atlas, a unique dataset of zoning texts tied to geospatial files that allow for georeferenced comparisons between the zoning laws adopted by 180 localities. We overlay the geographies of zoning districts on spatially differentiated demographic and economic indicators at the neighborhood level. Analyzing and comparing this information allows us to provide a comprehensive view of the relationships between zoning laws, property values, and residents' demographic and economic characteristics.Our research focuses on a state with stark disparities in residential land uses: only 2 percent of Connecticut's land is zoned to allow the by-right construction of multifamily buildings with three or more units per parcel, while 91 percent of its land allows only the construction of single-family housing by right. Our analysis reveals that suburbs and towns have the most restrictive zoning rules by several measures, while the largest cities more readily permit multifamily construction. We show that the residents of neighborhoods with mostly single-family zoning, on average, have significantly higher household incomes and are much more likely to be white, much less likely to be Black or Hispanic, more likely to have a bachelor's degree, and much more likely to own their homes than residents of neighborhoods where zoning allows for multifamily building construction. These findings paint a picture of a state where localities' zoning either divides or reinforces the division of residents by income, race, ethnicity, and education levels. We also apply a segregation index to explore the associations between zoning rules and neighborhood- and locality-level segregation. After controlling for other characteristics, we find that higher concentrations of high-income and white residents are associated with lower number-of-unit zoning policies. We also find that higher concentrations of low-income, Black, Hispanic, and other residents of color are associated with zoning allowing the construction of two or more housing units per parcel and higher shares of renter-occupied housing.Together, these findings bring new insight into the relationship between zoning policy and residents' geographic distribution. Our results clearly point to the links between zoning laws, rental housing availability, and inequitable distributions of populations within and across jurisdictions. Policymakers considering how to improve access to opportunity while reducing income or racial segregation should evaluate the potential for altering local zoning codes to allow greater diversity of housing construction and tenure types in more places.