Editor’s note: This article, distributed by The Associated Press, was originally published on The Conversation website. The Conversation is an independent and nonprofit source of news, analysis and commentary from academic experts.
For decades, land-use regulation throughout the U.S. has stressed having single-family houses on large lots. This approach has priced many people out of the quintessential American dream: Owning a home. It also has promoted suburban sprawl – a pattern of low-density, car-dependent development that has dominated growth at the edges of urban areas since the end of World War II.
Now, however, Americans may be starting to question the wisdom of owning a house. In the past year, the Minneapolis City Council and the state of Oregon have voted to allow duplexes and other types of multi-unit housing in neighborhoods where only single-family houses can now be built. Democratic lawmakers in Virginia, who recently won control of their state’s Legislature, are seeking to enact similar legislation. And several Democratic presidential candidates have included changes to zoning laws in their housing policies.
Headlines have predicted big changes in housing. But we believe that although attitudes about suburban life may be changing, the move away from single-family zoning will be slow and difficult.
Sprawl’s heavy costs
Many elected officials are rethinking their zoning law because some of their constituents worry that single-family houses cost too much, are wasteful and can leave people isolated.
Researchers have shown that single-family zoning promotes discrimination and exclusion. Our research is about its environmental effects. Dozens of studies have shown that sprawl results in the use of a great deal of energy, mainly for transportation; occupies too much land; degrades air and water quality; reduces species diversity; and contributes to climate change.
We have examined how Oregon’s land-use policy affects residential density and Oregon’s troubles with housing affordability. Oregonians are known to be progressive and concerned about the environment. They hate density because they value privacy and space. But they also hate sprawl because it consumes valuable agricultural land.
In short, Oregon would seem to be the ideal starting point for policies meant to curb single-family zoning. One of its 19 statewide goals for land-use planning, which were adopted in the early 1970s, deals with housing by requiring cities to offer many types of housing. But exclusively single-family neighborhoods are still predominant.
In the early 1970s, in what came to be named “the quiet revolution in land use control,” some states started taking back from cities and towns the authority that they had previously over zoning. In 1973, Oregon created “urban growth boundaries” – a line of demarcation between urban and rural land uses – around each of its cities, along with other measures to contain growth and prevent sprawl.
Our research shows that this approach has helped contain urban growth and promote the efficient use of land. Single-family density in urban-growth boundaries, as measured by the number of single-family housing units per acre, has consistently increased since the zones were established. Statewide, single-family density increased 22% from 1993 to 2012.
Still, sprawl exists inside urban-growth boundaries. We have found that land exclusively zoned for single-family houses can hold only a maximum of eight to ten units for each acre. And as demand for houses exceeds the supply, lower-income families are being pushed into relatively inexpensive places far from their work. Up for Growth, a national coalition that advocates for dense development, estimates that only 89 housing units were built in Oregon for every 100 households formed from 2000 through 2015.
In short, housing is getting more expensive. A Harvard study from this year concluded that the supply of low-cost rental units (under $800 per month) in Oregon decreased by 44% between 1990 and 2017. Today, 63% of Oregon’s housing consists of stand-alone houses or detached single-family units.
And these causes for concern aren’t limited to Oregon. According to the Harvard Joint Center on Housing, 47% of renter households are paying more than 30% of their income in housing costs. Between 2000 and 2015, the U.S. underproduced 7.3 million units of housing, meaning that families throughout the country are struggling to find housing that is affordable and on offer. This shortage is in 22 states and the District of Columbia.
Public officials are recognizing that allowing only single-family houses also leads to fairness concerns. Single-family zoning segregated neighborhoods after World War II by excluding black families, who could not afford to buy single-family homes, from middle-class white neighborhoods.
Today the demand for small, connected houses – including duplexes, triplexes and quadplexes – within walking distance of services is increasing. People like living this way, but as the architect and urban designer Daniel Parolek has shown, regulatory barriers deter builders from producing more houses of these types, which he calls the “missing middle.” As Parolek points out, many of the diverse housing types that are common in older neighborhoods, such as duplexes and triplexes, are illegal under most current zoning codes.
A modest but important start
All of these factors helped drive Minneapolis and Oregon to move away from single-family zoning and allow more housing types. But for all of the attention that these actions have received, we predict that they will have a modest effect.
Housing markets are complex and are affected by much more than zoning. One big question is whether costs will decline if policymakers encourage the construction of diverse “missing middle” dwelling types.
But this does not mean that changing zoning policies is misguided. Promoting the construction of broader ranges of housing gives rise to vibrant neighborhoods, reduces the conversion of farm and forest land for suburban development, reduces infrastructure costs and helps provide fair housing opportunities to all.
Robert Parker is co-director of the Institute for Policy Research and Engagement at the University of Oregon.
Rebecca Lewis is an associate professor of planning, public policy and management at the University of Oregon.