This article is an excerpt from the upcoming book, Escaping the Housing Trap: The Strong Towns Response to the Housing Crisis, written by Charles Marohn and Daniel Herriges. It appeared on StrongTowns.com on January 4, 2024.
Somerville, Massachusetts, is a thriving city. It has, in spades, the attributes that the median city planner and real estate professional alike will tell you are in great demand and short supply in 2020s America: walkability, vibrancy, sense of place.
Adjacent to central Boston, Somerville is known for top-tier educational institutions, a robust arts and culture scene, and lively civic squares surrounded by locally owned shops and restaurants.
Unsurprisingly, the city’s attractive lifestyle comes at a price. As of this writing, there are dozens of homes for sale in Somerville listed for over one million dollars.
Such a price ought to be a clear signal that there is ample market demand for a place like Somerville. According to economic theory, developers should respond by building more housing in Somerville, and by creating more blocks and neighborhoods that resemble the most in-demand parts of Somerville.
There’s only one problem: they largely can’t.
In 2015, Somerville’s city planners undertook a study to find out which of the city’s existing residential properties conformed to Somerville’s own zoning code. The number of fully zoning-compliant lots in the city of 80,000 people was a surprise to everyone: there were only 22.
The city of Somerville, it turned out, had declared itself illegal. There was no single reason for this but a combination of requirements working in tandem. These included rules about building height, lot size, density, and the positioning of buildings on a lot. Nearly every property was in violation of one or more rules.
Somerville’s zoning code was clogging the city’s planning bureaucracy and choking its growth. It was legal to continue to use an existing building for a use that had been in effect before the code was created. But as soon as a property owner wanted to undertake so much as a routine expansion—a front porch, a back deck, a finished basement—they were liable to trigger a complicated and costly set of inspections and requirements. And anyone seeking to build a new building would encounter even more limitation on where it could be and what they could do.
It would be one thing if this situation were an oddity, a case of bureaucracy run amok or unusually incompetent city staff. But “illegal neighborhoods” are not uncommon. An estimated 54% of homes in San Francisco are in buildings that could not legally be built today. Even in Manhattan, which has among the most permissive standards in the U.S. for density and height, 40% of buildings are nonconforming.
It would be another thing if Somerville’s zoning reflected some sort of informed consensus that the city’s historic form is not up to standards of adequate habitation, in the same way that a car manufactured in 1970 would not meet today’s safety or emissions standards. But no one is making this argument, and the prices of those historic homes would seem to refute it.
And yet the kind of place that Somerville typifies is, in fact, illegal to reproduce almost anywhere in America. That kind of place is the kind we built everywhere under the traditional pattern of development that prevailed before the Great Depression. It is compact and fine grained, a city where needs can be met on foot. It has a varied mix of homes, businesses, and modest apartment buildings on tightly spaced lots.
Such places, today, are mostly cities under glass, frozen in time. We have almost entirely stopped building more of them or expanding on those that exist.
Yet surviving “illegal” buildings are all around us. They are not unfamiliar or exotic to modern Americans. Older neighborhoods are peppered with residential structures that predate modern zoning and would be illegal to replicate today. Within them, all sorts of Americans go about their lives peaceably.
Somewhere, perhaps near you, an extended family lives together in a duplex to share both housing expenses and childcare. A working-class family rents an apartment in an area where they could not afford to buy a home, securing access to a safe neighborhood with good schools.
Today, duplexes are illegal to build in most American neighborhoods. So are apartment buildings.
Somewhere nearby, an aging parent or a 20-something couple live in an accessory dwelling unit (ADU) behind a larger home. You may know these backyard cottages as mother-in-law units, granny flats, casitas, carriage houses, garage apartments—a variety of vernacular terms reflecting the diverse circumstances in which these arose organically as a prior generation’s practical solution to housing needs.
Backyard cottages, like duplexes, are illegal to build in most American neighborhoods today. Where they still exist because their construction predated the zoning code, they are legally nonconforming: a clinical bit of planner-ese that evokes the tone in which a 1950s sociologist might have spoken about deviant subcultures.
Many of the neighbors of these buildings have likely never given a single thought to their illegality. The dissonance between our zoning codes and our cities as they actually exist is American planning’s best- and worst-kept secret.
Most Americans have heard of zoning. But to the extent that they know anything about it, it’s what they know from games such as SimCity or Cities: Skylines. That is, zoning is part of the basic order of the city: a simple, universal, and presumably sensible regulation put in place to protect the character of our neighborhoods. Zoning, we are told, is the reason your home is unlikely to be menaced by a smokestack.
Most countries around the world have zoning in some form, but the North American version is quite exceptional. It is unique in the rigidity with which it separates different uses of land into distinct, mutually exclusive districts. It is also unusual in the primacy it gives to one form of housing: the detached single-family house.
If zoning began as a tame creature, today it is a huge, multi-headed hydra. It is an enormous and unruly beast that has grown beyond the designs or imagination of its early proponents. And zoning constitutes a massively distorting influence on the shape of our cities and towns, including where we build housing, what we build, and who gets to build it.
Editor’s note: Somerville has updated their zoning code since this excerpt was originally written. Still, this case study is illustrative of a common problem throughout the U.S.
This article is an excerpt from the upcoming book, Escaping the Housing Trap: The Strong Towns Response to the Housing Crisis, written by Charles Marohn and Daniel Herriges. Pre-order your copy today.
Daniel Herriges serves as Senior Editor for Strong Towns, and has been a regular contributor since 2015. He is also a founding member of the organization. Daniel has a Masters in Urban and Regional Planning from the University of Minnesota, with a concentration in Housing and Community Development.