Great Migration Pushed Northern Cities Toward Exclusionary Zoning

Why This Question Matters

Cities across the United States routinely limit where multifamily housing can be built, shaping neighborhood composition, affordability, and who can live in a city. Alexander Sahn asks whether those land-use limits arose primarily from homeowners’ economic interests or whether they were also a deliberate tool to preserve racial segregation as Black migrants arrived in Northern cities during the Great Migration.

New Zoning Data Across Cities

Using newly assembled administrative zoning records, the study documents that the median central city in the non-Southern United States allowed multifamily housing on just 13% of residential land—an unusually small share that helps explain persistent low-density neighborhoods.

Historical Migration as a Natural Experiment

Sahn leverages exogenous variation in Black migration to Northern cities between 1940 and 1970 as a source of plausibly causal change in local racial composition. The paper links that historical demographic shock to contemporaneous zoning choices and combines the zoning data with public-opinion surveys to explore the political mechanisms behind policy change.

Key Findings

• Cities that experienced larger increases in Black residents during 1940–1970 subsequently zoned less land for multifamily housing, consistent with tighter limits on new, higher-density development.
• Analysis of public-opinion surveys shows that white urban voters in migration-impacted areas reported experiencing desegregation and became more racially conservative about housing policy, suggesting constituent preferences shifted in ways that favored exclusionary rules.
• Together, the zoning and survey evidence indicate that exclusionary zoning was not only about preserving property values in the abstract but also operated as a policy response to racial threat, embedding residential segregation into land-use law.

What This Implies

The findings show how demographic shocks and racial attitudes can shape durable municipal policy: zoning rules that look like neutral land-use regulations can function to limit integration. This helps explain the historical roots of today’s low-density, exclusionary neighborhoods and highlights political obstacles to zoning reform aimed at increasing housing supply and reducing segregation.