Planopedia

Single-family zoning refers to zoning policy that restricts development in an area to single-family homes. These policies are sometimes accompanied by a minimum lot size, and face criticism for preventing increased density, exacerbating the housing affordability crisis, and excluding low-income households, renters, and people of color from areas of opportunity.

First proposed in the early 20th century, single-family zoning was used as a tool to preserve home values and maintain public health and safety. "Zoning advocates argued, for example, that channeling residential development into neighborhoods of detached single-family houses far removed from shops and offices would be a boon to Americans’ health." Single-family zoning excludes not only different housing types but also businesses, making communities less walkable by denying opportunities for small local businesses such as corner stores and neighborhood banks. According to Jessica Trounstine in Segregation by Design, in early zoning rhetoric "the apartment house is [viewed as] a mere parasite" and corner stores are seen as "vectors of disease and disorder." 

The first single-family zoning law was passed by the city of Berkeley in 1916. The measure was promoted by the developer of the Elmwood neighborhood, who wanted to preserve home values in his development by preventing Black families from moving into adjacent areas. Although developers could, at that time, control who moved into their neighborhoods via racial covenants, another tactic was needed to ensure racial homogeneity in surrounding neighborhoods. Urging the city to pass single-family zoning in the surrounding areas let Elmwood's homeowners essentially dictate housing policy beyond their community's boundaries. The new law also prohibited a proposed Black dance hall and made the neighborhood more exclusive and expensive. 

After having earlier struck down racial covenants, the U.S. Supreme Court ruled in favor of proposals banning apartment buildings and allowing only single-family homes in certain areas in 1926, even though many supporters of those plans transparently pushed the zoning measures as a means to segregate their communities. After the Fair Housing Act mandated that the federal government affirmatively promote affordable housing in high opportunity areas, communities doubled down on single-family zoning as a more euphemistic tool for controlling the demographics of an area.

Today, around 75% of land zoned for housing in major U.S. cities is zoned for single-family housing. In California, single-family zoning accounts for between half and three-quarters of all developable land in the state. According to a survey from the National Bureau for Economic Research, 94% of U.S. communities have a minimum lot size provision, and the average minimum size is growing—a troubling trend for those who hope to see more affordable homes and multi-unit buildings on small lots.

Single-family zoning sometimes also occurs in areas designated as historic preservation districts, where historic designation prevents zoning changes and increased density regardless of the area's affordable housing needs. 

Rethinking the policy

Single-family zoning can lead to exclusivity by prohibiting more affordable housing types such as duplexes and multi-family apartment complexes, shutting out low- and middle-income households, and preventing property owners from using creative solutions to build additional housing units. Combined with minimum lot size, single-family zoning establishes de-facto income minimums for certain neighborhoods.

Culturally ingrained as the epitome of the "American dream," the rise of the single-family residential neighborhood has also led to rising housing costs, sprawl, and increased car dependence that contributes to higher greenhouse gas emissions, longer commutes, and more disconnected communities. A growing number of people believe that single-family zoning no longer makes sense considering the challenges faced by cities when it comes to housing affordability, inequality, and climate change. In the last few years, housing activists across the country have started to question single-family zoning ordinances, leading to policy changes in several cities and states including Minneapolis, Oregon, and the place where it all started, Berkeley. While opponents fear the loss of historic neighborhoods and important local architecture, others argue that even more reform is needed to undo the damage of the exclusionary and racist policies that have shaped the design and demographics of cities and suburbs for the last century.

Rezoning efforts include more permissive laws for Accessory Dwelling Units, allowing housing to be subdivided into duplexes/triplexes/fourplexes, as well as permitting for higher-density and mixed-use apartment buildings. These types of housing are also described as "Missing Middle Housing," mid-density buildings that increase density and walkability while preserving the character of traditionally low-rise neighborhoods.