Missing middle housing
Based on Wikipedia: Missing middle housing
Walk through almost any American or Canadian city built before World War Two, and you'll notice something curious: a kind of building that barely exists anymore. Not single-family houses. Not towering apartment complexes. Something in between—duplexes with a shared front porch, rowhouses with stoops, triple-deckers where three families might know each other's names. These buildings used to be everywhere. Now they're largely illegal to construct.
That's the "missing middle."
The Vanishing Act
The term itself came from architect Daniel Parolek in 2010, but the phenomenon it describes had been quietly reshaping North American cities for decades. Medium-density housing—buildings with somewhere between two and roughly twelve units, scaled to fit comfortably alongside single-family homes—didn't disappear because people stopped wanting them. They disappeared because we made them against the law.
Consider what American cities looked like before this transformation. At the turn of the twentieth century, most urban areas weren't dramatically different from their European counterparts. Cities had compact footprints relative to their populations. Buildings typically stood three to seven stories tall. A ring of streetcar suburbs extended outward, but only modestly. Most residents, particularly those of lower and middle incomes, lived in dense environments within practical distance of their workplaces.
The arrangement had an elegant logic to it. People without much money often lived on upper floors of multi-unit buildings—elevators weren't yet common, so climbing stairs was the trade-off for cheaper rent. Merchants lived above their shops. Those with more resources might own a rowhouse or live in the new streetcar suburbs. Small owner-operated shops served their immediate communities. When you needed to go somewhere beyond walking distance, you took a bicycle, bus, streetcar, or train.
Only the wealthy lived the way most Americans are now expected to: in large houses set apart from the city, commuting in by private vehicle. For everyone else, the need to live near work imposed a natural limit on how much a city could segregate itself by class.
Then came the car.
The Suburban Revolution
The story of how America became car-dependent is partly economic and partly ideological. After World War Two, factories that had been producing tanks and military vehicles could be retooled to manufacture civilian automobiles at unprecedented scale. The price of car ownership dropped. Meanwhile, federal and state governments launched massive highway construction programs and began directly subsidizing the purchase of new suburban homes.
Levittown became the prototype: mass-produced single-family houses, each on its own plot, arranged in developments accessible primarily by car. It was the wealthy person's estate life, made affordable for the middle class—or at least for white middle-class families, since racial covenants and discriminatory lending practices ensured that Black Americans were largely excluded from this particular version of the American Dream.
But the shift wasn't just about economics. Policymakers of the era had begun to conflate dense urban living with poverty, crime, and moral decay. Small apartments and crowded streets came to seem like problems to be solved rather than efficient responses to the need for affordable housing near jobs. The solution, in this view, was to spread people out. Give everyone a yard. Replace walkable neighborhoods with car-dependent suburbs.
There's an extraordinary detail in this history that deserves attention: the legal definition of who belonged on the road had to be rewritten. Originally, American law held that everyone had an equal right to use public streets—pedestrians and vehicles alike. Automobile advocates campaigned to change this, inventing the very concept of "jaywalking" and successfully pushing to criminalize the act of crossing the street on foot.
Think about that for a moment. Walking across a street was perfectly legal until the car industry decided it shouldn't be.
The Zoning Lockout
The transformation of North American cities from medium-density to polarized landscapes of houses and towers happened through a specific legal mechanism: single-use zoning.
Municipalities adopted zoning codes that divided cities into districts with strict rules about what could be built where. Residential zones permitted only single-family homes. Commercial zones allowed only businesses. Industrial zones were for factories. And critically, the residential zones—which covered the vast majority of urban land—were designed around the assumption that everyone would drive.
This meant minimum lot sizes. Mandatory setbacks from the street. Requirements for off-street parking. Rules that made it mathematically impossible to build the duplexes, rowhouses, and small apartment buildings that had once been the backbone of urban housing.
The result was a cityscape split between two extremes. Downtown cores, influenced by the prestige of Manhattan and Chicago, became forests of skyscrapers devoted primarily to office use—Central Business Districts designed for workers to commute in by day and empty out at night. Everything else became suburbs: single-family houses with yards, connected by highways, serviced by strip malls and big-box stores.
The middle ground vanished. Not naturally. By design.
What We Lost
The consequences extend far beyond aesthetics.
Start with affordability. Medium-density housing is inherently less expensive to build than either single-family homes or high-rise apartments. These buildings typically use wood-frame construction rather than the concrete podiums required for taller structures. Units share land costs across multiple households. A larger pool of small local builders can participate in their construction, rather than only major developers with access to significant capital.
When cities make this type of housing illegal, they artificially constrain the supply of affordable homes. And because older buildings tend to filter down the income scale over time—becoming naturally more affordable as they age—the decades-long prohibition on new medium-density construction has compounded into today's housing crisis. We stopped adding to the supply precisely when we needed it most.
Then there's the question of walkability. Medium-density neighborhoods generate enough foot traffic to support small businesses: cafes, corner stores, barber shops, restaurants. These businesses in turn make neighborhoods more pleasant to walk in, creating a virtuous cycle. Big-box stores and strip malls, by contrast, require customers to drive—they can't survive on foot traffic alone because the surrounding population density is too low.
This brings us to what the sociologist Ray Oldenburg called "third places"—locations that are neither home nor work where people gather informally. The neighborhood bar. The coffee shop. The community center. The park with benches where neighbors actually sit. These places depend on proximity: they need to be easy to reach, close enough that visiting doesn't require planning a special trip.
In car-dependent suburbs, third places struggle to exist. Going anywhere requires getting in your car and driving there, which means every outing becomes deliberate rather than spontaneous. You don't bump into neighbors. You don't build the casual acquaintanceships that gradually become friendships. Some researchers have suggested this helps explain rising rates of loneliness and declining social cohesion—we've literally designed the opportunities for human connection out of our built environment.
The Environmental Price
Cars are remarkably inefficient at moving people through space. A single traffic lane carrying automobiles at rush hour can transport roughly 1,500 to 2,500 people per hour. The same lane configured for buses moves 4,000 to 8,000. A dedicated rail line can exceed 25,000.
Building cities around cars means devoting enormous amounts of land to moving and storing vehicles that spend most of their time parked. It means more pavement, which increases flood risk and urban heat. It means longer commute times, which have proven stubbornly resistant to improvement—adding highway capacity simply induces more driving, a phenomenon known to transportation planners as induced demand.
The environmental geographer Laura Pulido has documented how the historical processes of suburbanization concentrated pollution and environmental hazards in communities that were excluded from the suburban expansion—predominantly communities of color. This represents another dimension of the cost: environmental racism baked into the structure of our cities.
A Different Approach
Japan presents an instructive contrast.
Japanese cities use zoning—but not the single-use zoning that dominates North America. Instead, Japanese zones are defined by the most intense use permitted. Uses of lesser intensity are automatically allowed in zones permitting higher intensity uses, but not vice versa. This creates what planners call "nested zoning."
In practice, this means that residential uses can occur in commercial and industrial zones (where developers choose to build housing), but heavy industry can't locate itself in residential neighborhoods. The result is naturally mixed-use development: apartments above shops, small businesses nestled among houses, and—crucially—no legal prohibition on the medium-density buildings that have disappeared from North American cities.
Rather than trying to plan exactly where medium-density housing should go, Japanese planners focus on creating conditions that make it attractive for landowners to build. Lot size minimums are minimal or nonexistent. Parking requirements are modest. The building code focuses on ensuring adequate light and ventilation between structures rather than mandating specific housing types.
The outcome is cities that feel remarkably different from their North American counterparts: dense and walkable, served by efficient public transit, with housing at a range of price points and sizes.
Signs of Change
Something is shifting in North American cities. The phrase "missing middle housing" has moved from planning jargon to mainstream political discourse. Several jurisdictions have begun loosening the zoning restrictions that made this building type illegal.
Oregon eliminated single-family-only zoning statewide in 2019. California has passed a series of laws making it easier to build accessory dwelling units—small secondary homes on existing residential lots. Minneapolis became the first major American city to eliminate single-family zoning entirely, permitting triplexes on any residential lot.
Transit-oriented development has emerged as one strategy for reintroducing medium-density housing. The idea is straightforward: build mixed-use developments around public transit stations, creating pockets of density that support and are supported by the transit infrastructure.
Critics point out that these developments often miss what made the old medium-density neighborhoods work. Large-scale transit-oriented developments tend to be built by a single developer, on consolidated parcels, with a few large buildings rather than many small ones. They can feel sterile and corporate—more like the suburbs and strip malls they're meant to replace than the organic urban fabric of pre-war neighborhoods.
The challenge, these critics suggest, isn't just to permit more density. It's to create the conditions—legal, financial, infrastructural—that allow density to emerge organically, building by building, parcel by parcel, through the decisions of thousands of small property owners rather than the master plans of a few large developers.
What Middle Housing Makes Possible
Consider what becomes possible when cities allow a genuine range of housing types.
A young couple can start out in a small apartment, then move to a larger unit in the same neighborhood when they have children, then perhaps to a rowhouse or duplex. Their parents, aging, can downsize to a smaller unit without leaving the community they've spent decades in. A grandmother can add an accessory dwelling unit to her property, generating rental income while keeping her granddaughter close by.
Families at different income levels can live in the same neighborhood, accessing the same schools and parks and transit. Small entrepreneurs can afford to open shops serving their immediate neighbors rather than requiring customers to drive from across the city. People can walk to get groceries, meet friends at a nearby café, and know their neighbors' names.
This isn't nostalgia for some imagined past. It's a recognition that the housing arrangements Americans treated as normal for most of the twentieth century were actually a radical experiment—one that we're now living with the consequences of.
The good news is that the experiment was a choice. And choices can be unmade.
The Property Rights Question
There's an interesting political dimension to the missing middle conversation that cuts across traditional left-right divides.
Some property rights advocates have embraced missing middle housing as an expansion of individual freedom. If you own a lot zoned exclusively for single-family housing, you're prohibited from building a duplex on it—even if that duplex would better serve your needs or the needs of your community. Loosening these restrictions, in this view, gives property owners more choice about how to use their own land.
Equity advocates, meanwhile, point out that restrictive zoning has historically functioned as a tool of segregation. Requiring large lots and banning apartments keeps housing prices high, effectively excluding lower-income residents from certain neighborhoods. Permitting more diverse housing types can help undo some of this exclusionary effect.
The politics don't map neatly onto existing coalitions, which may explain both the opportunity and the difficulty of reform. NIMBY opposition—the impulse to preserve existing neighborhood character against any change—exists across the political spectrum. So does YIMBY advocacy for more housing construction.
The Long View
Cities are slow to change. Buildings last decades or centuries. Infrastructure lasts longer. The choices made by mid-twentieth-century planners continue to shape where and how we live, even as the assumptions underlying those choices have been thoroughly discredited.
But cities do change. They always have. The urban forms we now treat as traditional—the rowhouse blocks of Philadelphia, the triple-deckers of Boston, the courtyard apartments of Los Angeles—were once innovations. They emerged because they made sense for their time and place, and they persisted because they continued to serve human needs.
The missing middle is called that because it used to exist. The question now is whether we'll allow it to exist again.