Will upzoning neighborhoods make homes more affordable?

An illustration of single-family homes, duplexes, triplexes, fourplexes, and tall apartments.

Cities and states across the country are proposing new upzoning
laws to combat the housing crisis. Will they work?

Housing affordability
is a growing issue in America, and
there’s a battle over how to fix it happening on blocks across
the country. Zoning—the rules that govern how cities use their
land—is on the front line.

Between 1986 and 2017, the median price of single-family housing
in the U.S.
rose from 370 percent of the median U.S. household’s yearly
income to 410 percent
, according to the Harvard Joint Center
for Housing Studies.
Eleven million American households spend more than half their
paychecks on rent and utilities
. The
number of cost burdened renters is on the rise
, especially
among middle-income households. The percentage of
“supercommuters”—meaning those who travel more than 90
minutes each way to work—has
Almost nowhere in the United States is it possible for a
minimum-wage worker to afford a two-bedroom apartment
. Each
year, an estimated
2.5 to 3.5 million people experience homelessness
Progressive coastal cities
rural America
alike are experiencing shortages of affordable

Recently, policymakers at the state and local levels across the
country have zeroed in on a culprit: zoning that limits development
to single-family detached houses in large swaths of America. From
the east and west coasts to the Midwest, lawmakers are beating the
drum for upzoning, which means changing single-family zoning codes
to allow taller and denser housing, like duplexes, triplexes,
accessory dwelling units (ADUs), and apartment buildings. In the
last few years, upzoning legislation has been introduced or passed
, and
. The
federal government has also expressed interest in pressing local
governments to relax zoning laws that prohibit multi-family

This week, California legislators are voting on SB 50, one of
the most high-profile upzoning bills to date, which proposes adding
density near transit. As of Wednesday,
the bill has not received the necessary votes to advance
, but
is in limbo as some lawmakers have yet to make their decisions.

But is upzoning enough to alleviate the housing shortage? To
answer that question, it’s important to know how single-family
zoning became perceived as the norm for housing—and how that’s
fueling the affordability crisis.

A brief history of zoning in America

At its most basic, zoning determines what you can build on a
parcel of land (land use) and how much building is allowed
(density). Zoning is the primary way cities manage and regulate
land. It varies in complexity from place to place, and can either
mandate specific uses—such as in New York City’s
mandatory inclusionary housing
that requires affordable units
in all new development—or prohibit them, like exclusionary

zoning ordinances that once enforced segregation

The widespread adoption of zoning codes in the United States
began in the early 20th century, as cities were urbanizing rapidly.
Zoning laws were created to prevent nuisances, like factories, from
entering desirable neighborhoods—an early form of “not in my
backyard.” When Los Angeles enacted its
first municipal zoning ordinance in 1904
, it prohibited “any
public laundry or wash house” from entering residential
districts. In
1908, LA divided all land into residential and industrial
, making it the first place to “zone”

In 1916, New York City enacted the first comprehensive municipal
zoning code after
concern about skyscrapers blocking light and air and a boom in
speculative development
. Cramped and overcrowded areas of the
city were portrayed by social reformers as
unhealthy and dirty
—a description with clear racial
overtones, since these were also areas where immigrants lived—and
less dense areas where light and air could enter were viewed as
healthier and safer. “It’s more difficult to keep a mixed
district containing stores and dwellings clean and sanitary than a
residential district,”
the city’s Commission on Buildings District reported in

Through the 1920s, it was common for neighborhoods to include a
variety of housing types—detached single-family houses, duplexes,
apartments, bungalow courts—and commercial uses, like corner
stores. But as zoning took off, it established primary uses for
neighborhoods, which sometimes segregated their populations, too.
The few experts who completed zoning codes in their cities were
called upon to consult on codes elsewhere. Their segregationist
views came with them, even though
the Supreme Court declared racial zoning unconstitutional

Robert Whitten, co-author of New York City’s 1916 zoning
ordinance and president of the American City Planning Institute,

believed that
“Bankers and leading businessmen should live in
one part of town; storekeepers, clerks, and technicians in another;
and working people in yet others where they would enjoy the
association with neighbors more or less of their own kind.” He
also worked on the 1922 zoning code for Atlanta, which helped pave
the way for the segregation that continues to define that city.
—the planner who developed St. Louis’s 1916
zoning code with the
goal of preventing movement into “finer residential districts…
by colored people
”—was hired to consult on over 500 zoning
codes and comprehensive plans over the course of his career,
including those for Pittsburgh, New Orleans, Kansas City,
, Louisville,
and Washington D.C.

Amid a growing labor movement—in
1919 more than four million workers participated in
—industrialists also pushed for homeownership as a way
to keep workers happy and more dependent on their jobs. “The man
owns his home, but in a sense, his home owns him, checking his rash
impulses,” stated the 1919 book Good Homes
Make Contented Workers
. Around the same time, the federal
government began promoting single-family detached houses as a way
to fight communism and promote capitalism in response to the Red
Scare. President Coolidge wrote a 1922 essay called “A Nation of
Homeowners,” which promoted single-family detached houses as a
patriotic ideal. This ideology continued under Hoover, who, in
1927, praised the growth of suburban neighborhoods: “The
tremendous post-war expansion of suburban areas with detached
houses which the development of the automobile has helped make
possible is one of the finest achievements of the present period of
increasing national prosperity.”

“The single family was put on a pedestal,” says Jenny
, a Brookings Institute expert on urban economics and
housing policy. “It was ‘Single-family neighborhoods should
only have single-family detached homes’ and a lot of this is
about preserving the property values of those homes. [Single-family
residential zoning] was about keeping away things that are
considered undesirable uses, which might lower property values.
There was also some pretty blatant intent to exclude lower-income
families, renters, and non-white families.”

Zoning now makes it illegal to build anything other than a
detached single-family home on most residential land in many of the
American cities with the most competitive housing markets and
strongest job growth, according to a recent
New York Times analysis
. Detached, single-family homes account
for 75 percent of all land zoned for residential use in Los
Angeles; 94 percent in San Jose, California; 81 percent in Seattle;
77 percent in Portland, Oregon; and 70 percent in Minneapolis.

In areas with high demand for new housing, some lawmakers and
economists believe, single-family zoning is a clear restriction on
supply, which is driving the price of housing up.

What is upzoning and why are lawmakers proposing it?

In response to the growing housing affordability crisis,
policymakers in many cities and states are trying to figure out how
to add more housing. The challenge is that buildings occupy most of
the land in cities. Upzoning opens up the capacity of this land for
more housing. There’s also a climate case for upzoning: Building
housing closer to transportation and jobs means people have to
travel shorter distances to work and shop, lowering vehicle miles
traveled and potentially allowing them to use public transportation
and walk in lieu of cars.

Upzoning means changing the zoning code to allow taller and/or
denser buildings. (This is different from a rezoning, which, in
addition to allowing bigger construction, changes land use, like
the New York City rezonings of the Williamsburg and Greenpoint
industrial waterfront to residential.) It increases the buildable
capacity of land, creating the opportunity to increase supply.

As Christopher
, managing director of the Harvard Joint Center for
Housing Studies, explains it, as long as there is sufficient demand
for housing, developers will build. The price of land, the cost to
build a home, and what the market is willing to pay for a home all
factor into a developer’s math. If the cost of land is low enough
that the developer can earn a profit, then the developer will
build. By increasing the number of units that can be built on each
parcel, upzoning lowers the cost of land per unit. But there’s a

“There’s a hope that if we upzone this land worth one
million dollars and now we can put two units on it, the land cost
is $500,000 [per unit],” Herbert says. “But as soon as you tell
me I can put two units there, it’s going to affect the price of
land since it becomes more valuable.”

A study
published in January 2019 in the journal Urban Affairs Review

analyzed the impact of new upzoning policies Chicago passed in 2013
and 2015 that allowed denser housing near transit stops. The

study concluded
that over a five-year timespan, upzoning
didn’t increase housing supply, but it did increase land

Proponents of upzoning argue that allowing denser construction
will encourage more housing supply, and as more supply enters the
market, housing will become more affordable through the filtering
, where even high-priced new housing can lower rents for
lower-income residents by reducing the competition for homes. One
challenge with this approach is that added capacity doesn’t
necessarily translate into added construction because developers
don’t always choose to build. Additionally, the housing market is
so severely pressured in different areas that
the filtering effect is highly unpredictable

Historically, upzoning has been used on a case-by-case basis in
cities. When Washington D.C. was planning its metro expansion in
the 1960s, for example, Arlington, Virginia, decided to
upzone the areas within a half mile of new stations
, resulting
seven mixed-use, walkable neighborhoods that are now in heavy

Recent legislation to upzone single-family residential areas en
masse focuses on so-called “missing middle
housing—a term coined in 2010 by
Berkeley-based architect Daniel Parolek
—which includes
accessory dwelling units, duplexes, fourplexes, townhomes, and

bungalow courts
. These housing types fall somewhere between
single-family homes and mid-rise multi-family buildings. When
designed thoughtfully, missing-middle housing adds density
without dramatically changing the characte
r of a

“The sort of ‘gentle density’ increases that are being
proposed now, we haven’t actually seen that much,” Schuetz

Some recent attempts at increasing density will be closely
watched in coming years to see what effect they have on housing
supply and costs.
Minneapolis’s 2040 Plan
, which passed the city council in
October 2019, allows duplexes and triplexes in all single-family
neighborhoods and
permits 5- and 10-story buildings along transit corridors
Because estimating the market’s response to these changes is
unpredictable, the city doesn’t know how much construction these
changes will lead to, though it predicts that areas near
universities, transit, parks, trails, and retail will see more
development first. “The general policy here was to ensure as much
land use flexibility as practicable,” says Heather Worthington,
Minneapolis’s director of long range planning.

Oregon’s House Bill 2001,
which passed in July 2019
, legalizes duplexes on all
single-family zoned land in cities with populations above 10,000.
In cities over 25,000, the bill legalizes triplexes, fourplexes,
attached townhomes, and some
“cottage clusters”
in areas zoned single-family
residential. October also saw changes in California:
Governor Gavin Newsom signed several housing bills
, including

AB 68
, which allows one ADU and one junior ADU on lots zoned
for single-family residential. Cambridge, Massachusetts, is
considering an “affordable
housing overlay
,” which means allowing upzoning only if the
new units are 100 percent affordable.

The biggest proposed upzoning legislation is
California’s SB 50
, which
failed to receive enough votes to move the measure forward on
January 29
. Also known as the More Homes Act, it
called for cities and municipalities to add more housing near
transit hubs
. Proposed by
state Sen. Scott Wiener
, the bill gives local governments the
option to create their own plans or use a default zoning plan from
the state. The bill also includes requirements that local plans
pair low-income housing development with market-rate
mandatory inclusionary provision
—and removes parking
minimums. Another provision forbids the demolition of buildings
that have housed renters in the past seven years. Because that is a
data point that is difficult to quantify, and there’s currently
no way to measure that provision, predicting the overall impact of
SB 50 is very difficult, according to experts at UC Berkeley’s
Terner Center for
Housing Innovation

“Fundamentally, upzoning is making it legal to build the kind
of housing we used to build,” says Brian Hanlon, an advocate for
expanded rental housing construction and the president and CEO of
California YIMBY, an organization co-sponsoring SB 50. “We’re
not talking about building skyscrapers. We’re talking about
building the type of walkable missing middle housing California
used to build until we stopped building it. And that was when the
crisis skyrocketed. These old neighborhoods that were really nice,
we should be building more of them.”

There was no guarantee, however, that SB 50 would result in
upzoning that looks like older neighborhoods: Local land conditions
and existing parcel size will determine what can be

A recent
from the Terner Center for Housing
and the Urban Displacement
, two research groups at the University of California,
Berkeley, explored how local factors might influence SB 50’s
impact. It concluded that because builders will have to work around
small parcel sizes and existing buildings, “Manhattanization”
of areas is unlikely.

In December 2019, Virginia Del. Ibrahim Samirah introduced HB
152, which would allow duplexes to be built on any land in the
state zoned for single-family residential without any special
permitting requirements. Most new
housing in Virginia is suburban sprawl
, which contributes to
longer commutes, more carbon emissions, and increased expenditure
on municipal services like police, fire, water, and sewage, since

service area and cost expand significantly with sprawl
. Samirah
believes upzoning will help municipalities add housing without
increasing infrastructure costs. He also believes that upzoning
would increase the value of a homeowners’ properties, since they
would be able to build a second unit on land to generate rental
income. (However, some might argue that distance from neighbors is
what people will pay more for, and the added units could detract
from neighborhoods as a whole.) The state legislature
tabled the bill on January 23
, which means it might come up for
debate in the future..

According to Delegate Samirah, the current way affordable
housing is constructed in his state isn’t working. “There are a
lot of very expensive solutions to our housing crisis in Virginia,
and it seems like throwing money at the problem is the solution,”
he tells Curbed. “People are advocating for Housing Trust Fund
money to develop affordable housing and it’s led to very modest
results in affordable housing. The same with incentivising
developers to set aside affordable units.” (Since its inception
in 2012, the Virginia Housing Trust Fund has contributed money to
47 projects that have created or preserved 3,000 affordable

Inspired by Oregon’s upzoning bill, Nebraska state senator
Matt Hansen introduced one for his state in January 2020 called

Source: FS – All – Architecture 10
Will upzoning neighborhoods make homes more affordable?