Estimating the Housing Supply, Affordability, and Transit Ridership Impacts of Corridor- vs. Transit Area-based Upzoning in California

Project Description

California’s housing affordability and transit ridership crises are heavily influenced by how cities zone for new development. In an effort to accommodate growth while minimizing political opposition, some jurisdictions propose corridor-based upzoning — concentrating new housing along major roads — instead of more expansive area-based upzoning that extends into surrounding neighborhoods. This project uses scenario testing to evaluate the relative impacts of these two approaches on housing capacity, affordability, and transit access across several California metro areas. Using parcel-level data on zoning, land use, property value, and neighborhood characteristics, the research team estimates and compares the gross, “realistic,” and “highly feasible” housing capacity created by each upzoning strategy. They also assess breakeven rents for new housing, implications for publicly subsidized affordable housing, and expected effects on population density and transit ridership. By holding total added capacity constant across the two scenarios, this project also reveals the trade-offs between wider but lower-intensity area-based reforms and narrower, higher-cost corridor-based alternatives. This research equips planners, advocates, and policymakers with evidence to assess how zoning reform strategies shape housing affordability, walkability, and equitable transit access — and help guide decisions about where and how California should build more homes.