Evidence of Disparate Impact in Existing Zoning Structures

Nearly every city in the United States adopted local zoning law in the 20^th century. During the 21^st century, discussions surrounding zoning’s discriminatory legacy have steadily increased. Scholars, policymakers, community leaders, and practitioners contend that cities used zoning laws to divide neighborhoods by race and economic class. These conversations often narrate specific experiences of marginalized communities with zoning. When the actions of government negatively impact protected classes, this is known as disparate impact. My research set out to measure the landscape of zoning law to determine if the existing conditions seen today meet a threshold of disparate impact, specifically relating to environmental justice.

In the field of environmental justice, the health implications of how land use patterns affect different communities are a central concern. Low-income households and people of color often bear the negative effects when hazardous land uses generate externalities. The role of zoning in placing these industrial and commercial land uses near residential areas across cities in the United States over the past 100 years was not previously explored in depth.  

I found that, particularly as it relates to housing stratification and household income, many communities are at a disadvantage through zoning placement. Perhaps due to lack of housing or neighborhood choice, zoning for hazardous land uses is clustered alongside these populations in many cities. Often, communities housing low-income households, people of color, and parcels for apartment housing serve as a buffer to protect whiter, wealthier, single-family neighborhoods from these land uses. These patterns reflect the 1930s federal Home Owners’ Loan Corporation redlining maps.

Zoning reform is currently dominating political, policy, and planning discussions. The federal government recently authorized a large grant program to improve the zoning in our cities. As cities spend funds to reform zoning codes and improve housing affordability, my research enacts special attention to how the zoning  of cities has perpetuated environmental injustices and how this can be changed to provide safe and healthy housing for all city dwellers.

Chris Quattro received their PhD in City and Regional Planning from the Weitzman School of Design. Quattro instructed the PennIUR’s 2023 Urban Undergraduate Research Colloquium course, is an Adjunct Associate Professor at Temple University, and is a research consultant for a private land use law firm in San Antonio, Texas.