Definition
Racial zoning is the mid-twentieth-century American practice of using ostensibly race-neutral zoning regulations, urban-renewal designations, infrastructure routings, and public-facility siting decisions to enforce or maintain racial segregation. Explicit racial zoning (laws that named race as a zoning criterion) was struck down by the U.S. Supreme Court in Buchanan v. Warley (1917). The practices that replaced it operated through facially neutral language while producing the same segregative effects.
Robert Caro's The Power Broker documents specific examples of racial zoning by routing — playground siting decisions, parkway-bridge clearances, expressway routings — that shaped New York's racial geography across Robert Moses's career.
Why racial zoning matters
The mechanisms
Racial zoning operates through multiple mechanisms, each individually defensible and together producing systematic segregation:
Single-family-only zoning. R-1 zoning (single-family detached homes only) became the dominant zoning category in postwar American suburbs. By restricting density, R-1 zoning prevented the apartment construction that would have housed lower-income (disproportionately Black) families. By the 2010s, single-family zoning covered roughly 75% of the residential land in cities like Los Angeles and San Jose.
Minimum lot sizes. Large minimum lot sizes (one acre, two acres, five acres) effectively required high incomes to enter the neighborhood. The income effect produced the racial effect.
Infrastructure siting. Where the city sites parks, schools, libraries, hospitals, and transit hubs shapes which neighborhoods get the goods. The 255-playgrounds-1-in-Black-neighborhood pattern Caro documents in The Power Broker is the canonical case.
Highway routing. Postwar urban expressways routinely routed through Black commercial corridors — the destruction of Hayti in Durham, the Brewer's Row in Detroit, the Auburn Avenue corridor in Atlanta, East Tremont in the Bronx. The routings were typically defended on cost-and-engineering grounds; the racial effects were predictable.
Urban-renewal designations. Title I slum-clearance designations targeted Black and Latino neighborhoods at rates far exceeding their share of urban population. The blight finding became, in practice, a proxy for racial composition.
The Caro documentation
The Power Broker documents the racial pattern in Robert Moses's New York work across several topics:
Playground siting (Topic 25 · Part 2, our chapter-55). Of 255 new playgrounds built in his first six years as Parks Commissioner, one was in a Black neighborhood (Stuyvesant Heights), and none was in South Jamaica or Harlem. Black-population neighborhoods received roughly 1% of new playground construction while representing roughly 5% of city population.
Pool siting. The mid-century pool program produced one pool in Harlem and none in Brooklyn's Black neighborhoods. The white-population pools were larger, cleaner, and better maintained.
Parkway bridge clearances (Topics 24-25). Parkway bridges were built low (typically 9 feet) to keep buses out. Bus passengers were disproportionately Black and poor. The exclusion was design choice.
Highway routing (Topics 36-38). The Cross-Bronx Expressway routing through East Tremont, despite an available alternative slightly to the north, is the most-documented case. Similar patterns repeat across the 13 NYC expressways.
Riverside Park per-mile spending (Topic 25 · Part 4). $8 million per mile south of 110th Street; $1.7 million per mile north of 110th Street (the Harlem-adjacent stretch). The 4.7x asymmetry was choice, not engineering necessity.
Modern persistence
Many of the mid-century racial zoning patterns persist in modified form:
- Single-family zoning remains dominant in most American suburbs and is increasingly being challenged in cities like Minneapolis (which abolished R-1 zoning in 2020), Sacramento, and Portland.
- Infrastructure-siting decisions continue to produce racially disparate outcomes. Modern transit construction, school siting, and park investment patterns remain unequal.
- Highway expansion continues to disproportionately route through Black and Latino neighborhoods (the I-94 expansion in Minneapolis, the I-10 in Houston).
- Disparate-impact litigation under the Fair Housing Act has had partial success but is constrained by Supreme Court doctrine that requires plaintiffs to identify specific policies and demonstrate causation.