Residential Zoning by Race:

Introduction

Residential Zoning by Race explores the evolution of single-family and multi-family zoning districts in Pittsburgh in the context of redlining and race in the city. The hypothesis of this project is that Pittsburgh’s current single-family and multi-family zoning districts follow a racial and exclusionary pattern that affects the housing choices available to White and Black residents. This pattern is tested through a GIS analysis of historic and current zoning maps, the 1937 Home Owner’s Loan Corporation (HOLC) map, and the historic racial compositions of the city by census tract.

Zoning is a local land use law that divides a municipality into different districts or zones, each with different use and density regulations. Zoning districts are often characterized by the uses they allow: residential, commercial, mixed-use, or industrial. The most common uses in residential zoning districts are single-family dwellings, rowhouses or townhouses, duplexes, triplexes, and apartments with four or more units. Most municipalities have multiple residential zoning districts.

In distinguishing the uses between the residential zoning districts, the municipality may take a hierarchical approach, a flat - or segregated - approach, or a combination of these approaches. In a hierarchical approach, the districts are ranked from most restrictive to least restrictive. As the districts progress toward least restrictive, they carry over all the uses permitted in the previous district and add more uses. In a flat approach, each use or group of uses has its own district where it is permitted and it is not permitted in any other district. In either approach, there is a zoning district that only permits detached single-family dwellings and no other residential use.

Nationally, there is a conversation to reform zoning because this exclusive single-family zoning district is contributing to the crises of housing availability and affordability. Minneapolis, San Francisco, and Connecticut are early adopters of this reform. Minneapolis and San Francisco are taking local approaches to eliminate the single-family zoning district and add more housing options in the single-family zone respectively. DesegregateCT is pursuing a statewide approach to zoning reform. More municipalities and states are taking on these and other reforms. In these changes to zoning, there is consensus that the exclusive single-family zoning district is a problem because it limits housing options and therefore housing affordability, but by focusing on this district type the conversation and solutions are limited. The single-family zoning district did not grow in isolation; it is important to consider the other districts, particularly the multi-family zoning district, in formulating a solution to the limitations and exclusions of the single-family zone.

Residential Zoning by Race seeks to expand this conversation about how to address the issues of housing availability and affordability by looking at the patterns of where single-family and multi-family zoning districts are located in Pittsburgh in the context of race and redlining. This pattern is important because zoning affects housing choice and affordability by designating what types of housing can and cannot be built or renovated in a given area.

In the context of this research, single-family zoning districts refer to districts that permit detached single-family dwellings exclusively while multi-family zoning districts refer to districts that permit housing types with 4 or more dwelling units.

This project was supported by the Pennsylvania Housing Finance Agency’s 2022 Kathy A. Possinger Housing Policy Fellow and Carnegie Mellon University Remaking Cities Institute’s Visiting Scholar program.

The following pages share the result of this research. Use the forward and back buttons to navigate the pages in order or click on the links in the contents below the buttons to jump to specific sections.