The old suburban frontier is closing. Here’s what the new one could look like.

But that abundance is already becoming a thing of the past. Across Sunbelt metros like Phoenix, Dallas, and Atlanta, housing supply growth has actually plummeted since the early 2000s, to rates almost as low as in hyper-expensive coastal cities, according to a new working paper by the leading urban economists Edward Glaeser and Joe Gyourko. Housing costs in these metros, while still lower than major coastal cities, have surged as a result.

Gyourko, a professor at the University of Pennsylvania’s Wharton School who decades ago documented slowing housing growth in superstar cities like New York and San Francisco, told me he was surprised to find the same pattern again unfolding, as if on a 20-year lag, in a region known for its lax regulations and enthusiasm for building things. Looking at the data, he thought, “Wow, Phoenix and Miami look like LA did as it was gentrifying in the ’80s.”

Although metro Phoenix, to unpack one example, is building a similar absolute number of homes as it did in the early 2000s, its population has grown by more than 58 percent since the turn of the century, so as a share of its current housing stock — the number that most matters, Gyourko says — it’s now building far less. If that trend continues even as demand to live in the Sunbelt remains undimmed, he said, “you would expect them to start to look more and more like Los Angeles.” By 2045, Arizona might be facing unaffordability and population loss crises much like those choking California today.

For many years, suburbs and exurbs have been the leading drivers of housing growth in Sunbelt cities, capturing most of the new population moving to the region. “The concepts ‘Sunbelt city’ and ‘suburb’ are nearly synonymous,” as historian Becky Nicolaides put it. But the slowdown in new housing builds across the region, Glaeser and Gyourko found, has been especially pronounced in well-off, low-density suburbs with desirable amenities like good schools. These suburbs have plenty of room to densify and welcome more neighbors — they just aren’t doing it.

“America’s suburban frontier,” the authors warn, “appears to be closing.”

The findings suggest that the fundamentals of housing in Raleigh, Orlando, or Miami are not so different from every other hot real estate market in the country. In most parts of the US with a growing economy and good jobs, the housing market has become badly broken to a degree that transcends the usual explanations, like regional differences in construction licensure rules or environmental review requirements — although those factors, without a doubt, matter.

So what’s really going on? Housing markets are complicated, and economic shocks like the Great Recession and the recent spike in interest rates have surely played a role. But the downturn in housing builds predates both those things, Glaeser and Gyourko found, suggesting a deeper cause. The Sunbelt may be confronting the same obstacle that has paralyzed growth elsewhere. It’s one of the most taken-for-granted facts of modern American life: the suburban model itself, and all its attendant political, regulatory, and financial problems.

Since the end of World War II, housing supply growth in the United States has overwhelmingly been driven by suburban sprawl radiating ever outward from city centers. Instead of building up, with density, we largely built out. But that engine may be running out of steam — and as a strategy for filling our national housing shortage, it’s failing spectacularly.

“It hasn’t been working in the supply-constrained coastal markets for four decades. What’s new is it looks like it’s starting not to work in the Sunbelt,” the country’s fastest-growing, most economically dynamic region, Gyourko said. “That changes the nature of America.”

The strangeness of housing policy in the US can be summed up like this: On a national level, we long for growth. On a local level, we do everything possible to smother it. That contradiction stems, in part, from our dependence on sprawl.

America is a nation of suburbs — that’s certainly not changing any time soon. And there’s nothing inherently wrong with suburbs, a housing arrangement as old and varied as human civilization. But to solve the housing crisis that is at the root of so many national problems, Americans will have to fundamentally rethink what the suburb is, and what it could become.

If you, like me, are too online for your own good, perhaps you’ve seen some version of this meme.

That image is a pretty accurate reflection of what American cities used to look like by default. Our suburbs, too, once looked much like this — remnants of the pattern can still be seen in places like Oak Park, Illinois (a suburb of Chicago), University City, Missouri (outside St. Louis), or Brookline, Massachusetts (neighboring Boston). Derived from the Latin word “suburbium,” meaning the area under or near a city, suburbs are so old that if you’ve ever thought about them, congratulations, you’ve been thinking about the Roman Empire.

Of course, what dense, older suburbs like Brookline or Oak Park have in common is that, like the cities they neighbor, they were largely laid out before mass car ownership. It was only relatively recently that suburbs became synonymous with a specific, car- and sprawl-oriented development style.

If the Western frontier defined American optimism in the 19th century, the suburban frontier defined it in the 20th. It’s a story you may already know in broad strokes: Before World War II, only a small share of Americans lived in suburbs, with the bulk living in rural areas and central cities. After the war, a complex alchemy of factors — including a national economic and population boom, federally backed mortgages that favored suburban homes, a Great Depression- and war-era housing shortage, and white flight — produced one of the greatest social and spatial transformations in the country’s history.

It would be easy, from our 21st-century perspective, to simply be bewildered by the urban planning decisions that fueled this wave of suburbanization. But those choices make a lot more sense when framed by the daily realities of mid-century urban life. Much of the prewar urban housing stock was genuinely terrible — many people lacked access to a full bathroom or even a flush toilet. Cities were still manufacturing centers and had the pollution to go with it. Americans who could afford to move were understandably pulled toward modern, spacious houses being built on an unprecedented scale in new tracts outside the city.

As this shift took place, the nature of the suburbs changed, from an organic extension of the city to what must have looked, to some at the time, like an alien planet. By 1970, most Americans dwelling in metropolitan areas — meaning a core city and its adjacent areas — were living in suburbs, and by 2010, most Americans were, full stop. Sunbelt cities like Phoenix and Las Vegas, which in the decades after World War II grew from little more than desert towns to megacities, developed in a particularly suburban, car-dependent form.

For a long time, that model worked well for a lot of people. But there was a problem that slowly made itself felt: Though they were themselves the product of a major transformation, postwar American suburbia relied on a restrictive set of rules that made suburban neighborhoods, once built, very difficult to change. Irrationally rigid regulations on housing remain in place across the country today. If you live in a single-family home, there’s a very good chance you’re banned from dividing your house into a duplex, redeveloping it into a triplex or apartment building, renting out a floor to a tenant, or opening a corner store.

These rules are set out by a system known as zoning: local regulations on what kind of things can be built where. Zoning, including single-family-exclusive zoning, first spread across the US in the early 20th century (before that, development was far more freewheeling and improvised). It reached its full expression after World War II, when it became a near-universal toolkit for shaping suburban America.

At first glance, the idea of zoning seems reasonable enough: Factories that emit toxic pollutants should probably be kept away from residential areas, for example. In practice, it has amounted to an extraordinarily heavy-handed, totalizing form of central planning controlling the fabric of daily life.

The overwhelming majority of residential land nationwide, as housing advocates are fond of saying, bans the construction of anything other than detached single-family houses — and that’s just the beginning. Zoning codes include legions of other rules, often including minimum size requirements (effectively banning starter homes) and mandatory parking spots for at least two cars. Apartments, in many areas, are zoned out of existence.

Suburbs exist all over the world. But the US, despite our national reputation for freedom and individualism, is relatively unique in having such a prescriptive segregation of land uses governing what people are allowed to do with what is, don’t forget, their own property, as Sonia Hirt, an architecture and planning professor at the University of Georgia, explains in her book Zoned in the USA.

We’re also unusual in granting privileged status to one specific, costly, and resource-intensive type of housing. “I could find no evidence in other countries that this particular form — the detached single-family home — is routinely, as in the United States, considered to be so incompatible with all other types of urbanization as to warrant a legally defined district all its own, a district where all other major land uses and building types are outlawed,” Hirt writes.

Suburban-style zoning has become widespread not just in suburbs proper, but also in core cities, many of which have adopted similar zoning codes that would have made their original growth and housing diversity impossible.

In that sense, suburbia isn’t just a specific place — it’s a mindset that’s become the default American settlement pattern. For mid-century home buyers, the costs of our suburban revolution were distant. But it didn’t take long for those costs to become felt nationally.

By rigidly defining what a community is allowed to look like, suburban zoning has done more than simply shape the physical form of our cities. It has also made it all but impossible for many communities to adapt and grow, as human societies always have, which has created severe distortions in housing markets.

“The suburban development model is built on the premise of stasis,” as Charles Marohn, a civil engineer and founder of the advocacy group Strong Towns, has put it. “These neighborhoods are frozen at their current number of households, no matter how much the surrounding city transforms. No matter how many jobs are created. No matter how desirable the area is or how high rents get,” he wrote in his recent book Escaping the Housing Trap.

That stasis quickly froze America’s most desirable metro areas, leaving them unable to build enough housing to meet demand. And when housing becomes scarce relative to the number of people who want to live in the community, it simply becomes more expensive.

Starting in the 1970s, home construction plummeted and prices soared in high-opportunity coastal cities because of restrictions on supply. Los Angeles, incredibly, downzoned its residential areas to such an extent between 1960 and 1990 that its total population capacity, as measured by the number of households it’s zoned to accommodate, declined from 10 million people to about 4 million, which is the level the city’s population has hovered around for the last decade.

The upshot is that many of America’s metropolitan areas have become dominated by what economist Issi Romem identified in 2018 as a “dormant suburban interior.” After World War II, cities and suburbs built out and out, mostly low-density single-family homes, before they largely stopped building altogether because zoning laws forced them to maintain an inflexible suburban form. Despite a few pockets of dense growth, most residential areas have been locked out of building incrementally and thickening up, even as demand to live there increases.

When a high-demand city refuses to allow greater housing density, the dynamic becomes progressively more toxic, not just because homes become more scarce, but also because market incentives can push developers to replace cheaper, smaller single-family houses with more costly McMansions (as opposed to, in a healthier market, building apartments or a set of townhomes that could house more people in the same amount of space, for less money per household).

In expensive cities, proposals to build more housing have, famously, often been blocked by angry neighbors (derisively called NIMBYs) who rely on a labyrinthine tangle of zoning laws to foil change that they don’t like. Now, that vicious cycle is poised to catch up with the South and Southwest, where, Glaeser and Gyourko believe, the decline in housing starts is likely a function of incumbent residents using regulation to make it harder to build.

“People in the Sunbelt, now that things have gotten big enough, they’ve figured out what the Bostonians figured out a long time ago, and the Angelenos,” Gyourko said. (And plenty of anecdotal evidence from local housing fights in the Sunbelt, Slate reporter Henry Grabar has noted, points to the same thing.)

Suburbia offered Americans an implicit bargain: Neighborhoods would never have to change, and we could instead accommodate more people by sprawling outward forever. To a great extent, that’s what’s happened, and it’s given us lots of single-family homes, but also a mind-boggling expanse of costly, deteriorating infrastructure, nightmare commutes, unrestrained greenhouse gas emissions, sedentary, disease-promoting lifestyles, and one of the highest car crash death rates in the developed world.

And we’re still in a housing crisis, because even in the sprawl-hardened, car-loving Southwest, sprawl has its limits. I put this question to Gyourko: Once the most distant, low-density exurbs of, say, Dallas declare themselves full, why don’t developers simply keep building the next ring of sprawl 50-plus miles away? “People don’t want to live that far,” he said (he later clarified that we don’t know the precise outer limit beyond which housing demand dwindles). Human prosperity has always depended on proximity to one another and to opportunity — and even in 2025, it still does.

The US has gotten steadily more suburban over the last century, but not uniformly so. In the early 2010s, many core cities, including Denver, Atlanta, and Washington, DC, grew faster than suburbs, due to a combination of younger generations’ increasing interest in urban lifestyles and a collapse in suburban home construction after the Great Recession.

Some of the most expensive homes in the country are consistently those located in dense, vibrant prewar cities, a clear signal that there’s high demand for those amenities. The revival of cities in the last few decades and the ongoing suburbanization of the US, Gyourko said, have both been happening at the same time.

Nevertheless, many Americans today, particularly post-Covid, still demonstrate a preference for the suburbs, for all sorts of reasons, including cheaper, larger homes for families of the kind that can be hard to find in cities. Americans are also spending more time alone and at home, and working remotely, which might increase their preference for spacious living quarters and diminish interest in urban life.

“There’s a pendulum that swings between loving the city and loving the suburbs, and it was absolutely shifting towards loving the city” in the 2010s, Romem told me. “And then the pandemic came and undid all of that.”

The disruptions of Covid also revealed the fragility created by American-style urban planning. Because of our preexisting shortage of about 3.8 million homes, a small share of Americans moving residences upended housing markets across the country.

Skyrocketing housing prices since the pandemic have given new fuel to the YIMBY (or “Yes in my backyard”) movement, which for more than a decade has sought to legalize the full diversity of housing options across the US. At bottom, YIMBYism is about freeing cities and suburbs from “the zoning straitjacket,” as M. Nolan Gray, an urban planner and senior director of legislation and research for the housing advocacy nonprofit California YIMBY, put it. In other words, he said: “Let people do things.”

“A city is the ultimate form of emergent order. A city represents the plans of the millions of people who live there and work there and play there and study there,” he said. “The basic instinct of zoning is that we can sit down and write out the exact appropriate types of uses, scale of those uses, and exactly where those uses can go — and it’s just such a presumptuous way to govern a city.”

The deeper implication is not just that we need more housing, but also that suburbs must be allowed to function like the miniature cities they are. They should be flexible enough to support a range of human aspirations — not just the hallmarks of stereotypical suburban life, but also the amenities of urban life. “No neighborhood can be exempt from change,” as Marohn put it.

Zoning exclusively for detached single-family homes, for example, has never made much sense, but it especially doesn’t make sense in 2025, when most Americans live in household sizes of two or one. Recognizing this, along with the severity of their housing crises, a number of cities and states have gotten rid of single-family-exclusive zoning in the last decade, along with other barriers to building housing. But because zoning codes are enormously complicated, repealing one barrier often isn’t enough to actually allow multifamily housing to get built — things like height limits or excessive parking minimums can still make it infeasible.

“Housing is like a door with a bunch of deadbolts on it,” Alli Thurmond Quinlan, an architect and small-scale developer based in Fayetteville, Arkansas, told me. “You have to unlock all the deadbolts, but as soon as you do, there’s an enormous amount of human creativity” that rushes in. She stresses that communities shouldn’t be afraid of going too far in repealing zoning rules, and that if anything, they should err on the side of going further.

Repeal minimum lot sizes, and a developer might find a way to build a cute narrow house in a gap between existing houses. Removing parking requirements made it possible to build this lovely set of densely clustered cottages — a development style that can blend harmoniously into suburban neighborhoods — in Atlanta at a significantly lower cost:

A single-family house, meanwhile, can be turned into a duplex:

Right now, what little density is being added to cities and suburbs often comes in the form of large apartment buildings (you may know them as “gentrification buildings”). There’s nothing wrong with those, and they have an important role to play in mitigating the housing shortage. Yet many people don’t want them built in single-family neighborhoods. Making it legal to incrementally densify single-family neighborhoods would allow suburbs to still look like suburbs, while greatly increasing their population capacity and their ability to support essential services like public transit.

“The dormant suburban sea is so vast that if the taboo on densification there were broken, even modest gradual redevelopment — tearing down one single-family home at a time and replacing it with a duplex or a small apartment building — could grow the housing stock immensely,” Romem wrote in 2018.

That style of neighborhood development — gradually over time, rather than building to completion all at once — also happens to be the secret to creating places with a visually appealing vernacular character, Romem said. “True character comes from layer upon layer over a span of many years, from many people’s different, disparate decisions. And that requires change.”

At the dawn of mass suburbanization, Americans had legitimate reasons for wanting to move out of cities, where substandard housing and overcrowding were still commonplace. But “one generation’s solutions can become the next generation’s problems,” as journalists Ezra Klein (a Vox co-founder) and Derek Thompson wrote in their book Abundance. The same forces that built the American dream 80 years ago are now suffocating it, inflicting profound pain on families across the country.

For me, this subject is personal: I’ve lived in apartments literally my entire life, a form of housing often treated as second-class, if it’s even permitted to exist. Some of that has been in cities, and some in a suburb. My immigrant mother worked incredibly hard to find homes that were safe, stable, and affordable to raise a child in. America gave me everything, but our national housing reality made things far more difficult for her than they needed to be.

There’s no shortage of wonky policy ideas about how to fix housing in the US — and they go far beyond just zoning codes (you don’t want to hear me get started on building codes or impact fees). We will also need a society-wide paradigm shift beyond policy: The financial and real estate industries will need to relearn models for supporting incremental densification, which, experts consistently told me, have fallen by the wayside since the entrenchment of sprawl and restrictive zoning.

More than that, our minds will have to open up to the inevitability of constant change, and abandon the idea that any of us has a right to veto our community’s evolution. As Marohn points out in Escaping the Housing Trap, “a community that has lost all affordable starter housing already has changed irreversibly. It is only the buildings that have not.”

The suburbs, above all, must be allowed to be plural. Across cultures and centuries, people of all sorts of circumstances have lived on the outskirts of urban life. Today, Americans of every social class seek homes in the suburbs. Some are affluent; many are not. Others want to be near a good school, a job, a support system, or simply a hard-won foothold of affordability. It’s not the role of a planning board or a legacy zoning map to decide. We don’t know what the future of the suburbs will be — but we can free them to become what we need of them.