If you looked up “Minnesota nice” in the dictionary you might see a picture of Charles Marohn. Affable and mild-mannered, Marohn, who goes by Chuck, grew up the eldest of three sons of two elementary school teachers on a small farm near Brainerd, the central Minnesota city best known as the backdrop for the movie Fargo. Marohn (pronounced “mer-OWN”) graduated from Brainerd High School, entered the National Guard on his seventeenth birthday, and went on to study civil engineering at the University of Minnesota. He now lives with his wife, two daughters, and two Samoyeds in East Gull Lake, a small city north of Brainerd. Marohn, forty, likes the Minnesota Twins, reads voraciously, and is a proud Republican. He’s the friendliest guy you’re likely to meet. He’s also a revolutionary who’s trying to upend the suburbs as we know them.

After graduating from college, Marohn went to work as a municipal engineer in his hometown and spent several years working with the small towns around the greater Brainerd area, putting projects together that would build roads, pipes, storm drains, and all kinds of infrastructure. It was the mid-1990s, the area was booming, and Marohn was laying down the systems that helped the area grow. “I built sprawl,” he now says.

Often his work required him to knock on the doors of residents, many of whom he knew from growing up, and tell them about changes that might impact their property. In order to make the town’s roads safer, he would explain, engineers were going to have to widen the road in front of their house or cut down a tree in their yard. When his neighbors would get upset and ask why or try to protest—the roads were hardly trafficked at all, and sparse enough to almost be rural, they would point out—he’d explain that the town was required to make these changes in order to comply with the book of engineering standards to which it had to adhere. The code, put in place by the town but derived from state and national standards, dictated that roads must have an ample “recovery zone,” or a wide berth to accommodate cars that veer off the road, and that drivers have improved “sight distance,” the distance a driver needs to be able to see in order to have enough room to be able to react before colliding with some- thing in the roadway. When residents pointed out that the recovery zone was also their yard, and that their kids played kick ball and hopscotch there, Marohn recommended they put up a fence, so long as it was outside the right-of-way. He was sorry, he told them, but the standards required it. The trees were removed, the roads widened, the asphalt paved and repaved. “I never stepped back from my own assumptions to consider that I wasn’t making anything safer,” Marohn says. “In reality, I was making their street more dangerous, and in the process, I was not only taking out their trees, I was pretending I knew more than them.”

In 2000, Marohn found himself assigned to ﬁx a leaky pipe in Remer, a small town north of Brainerd. It was a routine project, but it would ultimately lead him to an epiphany. A sewer pipe that sat under a highway had a leak that was allowing clean groundwater to ﬂow in. That meant that the clean water was getting pumped out to sewage treatment ponds, which were exceeding their capacity and would soon overﬂow. It was easily ﬁxable, but it would cost $300,000, a hefty sum considering the town’s total budget for such projects was $120,000 a year; sure enough, the town said no. But the pipe was going to cause the sewage ponds to overﬂow, undermine the dike, knock down its wall, and pour into the neighboring river “in like a catastrophic way,” Marohn says. So he decided to ﬁnd a federal grant to pay for it.

He discovered that the project was too small; grant agencies didn’t seem to be interested in a $300,000 renovation, he found, presumably because it wasn’t worth the time in administration costs. So he expanded the project, proposing the government pay not just to ﬁx the pipe but also to extend the sewers, expand the size of the pumps, and more, at a cost of $2.6 million. The grant agency gave the green light; the state and federal government put up all the money except for

$130,000, which the U.S. Department of Agriculture ﬁnanced at below-market rates over a forty-year time period. Marohn was hailed a hero. “Everybody was super thrilled with me because I got this project approved out of nowhere,” he says. And since the project would connect more homes, it would allow the town to promote the fact that it was creating capacity for the city to grow.

But over the next several years, as Marohn went back to Remer to do additional work—he had by then gotten a degree in urban planning—and saw that the town was in the process of doing a similar project with their water system, he realized he had created an unsustainable ﬁnancial situation. Thanks to the leaky pipe he ﬁxed, the town now had to bear the maintenance costs of a system that was double the size of the one it had before. “I bought them time,” he says, “but I gave them a giant unfunded liability.”

Marohn started questioning the rationale of this kind of system. The government paid the up-front costs of the massive project, but there was no accounting for the significant cost to maintain the system. The town’s property taxes wouldn’t come close to covering those costs, which meant the city would ultimately need to take on more debt. And the system was likely to need replacing well before forty years were up—the duration of the ﬁnancing he’d procured—which would require an investment of equal or larger size. Marohn began to wonder whether all the work he’d been doing to supposedly help the city grow was really necessary or whether it was going to end up hurting it and, on top of that, whether the roads he was helping to “improve” were designed to accommodate the way people lived or were that way simply because the planning books said that was the way they had to be built.

He connected with a few friends in the local planning community who shared his concerns. In November 2009 they started a Web site called Strong Towns to start raising questions about America’s approach to land use and the ﬁnancial impracticalities suburban sprawl encourages. Rich in case studies and educational materials, Strong Towns lobbies for communities that are ﬁnancially productive and grow responsibly. But it’s also a screed against what Marohn sees as development patterns that go against the logic of design, ﬁnance, and the best interests of residential communities and everyday Americans.

One night soon after he started the Web site, Marohn wasn’t sure what to write about, so he composed a blog post on his experience tearing down trees in his neighbors’ yards, an idea that had been bouncing around in his head for a while. Declaring his work “professional malpractice,” he described how the wider, faster streets he was sent to build weren’t only ﬁnancially wasteful but unsafe. “In retrospect, I understand that it was utter insanity,” he wrote in the essay, which he called “Confessions of a Recovering Engineer.” “Wider, faster, treeless roads not only ruin our public places, they kill people,” he wrote, referring to statistics of traffic deaths each year that, in his view, were a direct result of poor design. He penned the piece in less than an hour and went to bed. When he got up, his in-box was full of comments from people in the planning community with whom his words had resonated.

The Web site soon became a nonproﬁt, which became a series of podcasts, videos, and live neighborhood events around the country called the “Curbside Chat.” A local nonproﬁt threw in three years’ worth of funding, and in mid-2012 Marohn quit his job to focus on Strong Towns, which is now a robust site packed with in-depth articles, podcasts, a Curbside Chat companion booklet for public officials, and a “Strong Towns University” section with instructional videos featuring Marohn and his partners discussing things like the ins and outs of wastewater management. Marohn’s work has brought him attention within the planning community; he now travels all over the country speaking at conferences, hosting Curbside Chats, and spreading his message. But all, he says, for the greater good. “We’re not bomb throw- ers,” he says. “We like to think of ourselves as intellectual disruptors.”

Marohn primarily takes issue with the ﬁnancial structure of the suburbs. The amount of tax revenue their low-density setup generates, he says, doesn’t come close to paying for the cost of maintaining the vast and costly infrastructure systems, so the only way to keep the machine going is to keep adding and growing. “The public yield from the suburban development pattern is ridiculously low,” he says. One of the most popular articles on the Strong Towns Web site is a ﬁve-part series Marohn wrote likening American suburban development to a giant Ponzi scheme.

Here’s what he means. The way suburban development usually works is that a town lays the pipes, plumbing, and infrastructure for housing development—often getting big loans from the government to do so—and soon after a developer appears and offers to build homes on it. Developers usually fund most of the cost of the infrastructure because they make their money back from the sale of the homes. The short-term cost to the city or town, therefore, is very low: it gets a cash infusion from whichever entity fronted the costs, and the city gets to keep all the revenue from property taxes. The thinking is that either taxes will cover the maintenance costs, or the city will keep growing and generate enough future cash ﬂow to cover the obligations. But the tax revenue at low suburban densities isn’t nearly enough to pay the bills; in Marohn’s estimation, property taxes at suburban densities bring in anywhere from 4 cents to 65 cents for every dollar of liability. Most suburban municipalities, he says, are therefore unable to pay the maintenance costs of their infrastructure, let alone replace things when they inevitably wear out after twenty to twenty-ﬁve years. The only way to survive is to keep growing or take on more debt, or both. “It is a ridiculously unproductive system,” he says.

Marohn points out that while this has been an issue as long as there have been suburbs, the problem has become more acute with each additional “life cycle” of suburban infrastructure (the point at which the systems need to be replaced—funded by debt, more growth, or both). Most U.S. suburbs are now on their third life cycle, and infrastructure systems have only become more bloated, inefficient, and costly. “When people say we’re living beyond our means, they’re usually talking about a forty-inch TV instead of a twenty-inch TV,” he says. “This is like pennies compared to the dollars we’ve spent on the way we’ve arranged ourselves across the landscape.”

Marohn and his friends are not the only ones warning about the ﬁx we’ve put ourselves in. In 2010 the ﬁnancial analyst Meredith Whitney wrote a now-famous report called The Tragedy of the Commons, whose title was taken from the economic principle that individuals will act on their own self-interest and deplete a shared resource for their own beneﬁt, even if that goes against the long-term common good. In her report, Whitney said states and municipalities were on the verge of collapse thanks in part to irresponsible spending on growth. Likening the municipalities’ ﬁnances and spending patterns to those of the banks leading up to the ﬁnancial crisis of 2008, Whitney explained how spending has far outpaced revenues—some states had spent two or three times their tax receipts on everything from infrastructure to teacher salaries to libraries—all ﬁnanced by borrowing from future dollars.

Marohn, too, claims we’ve tilled our land in inefficient ways we can’t afford (Whitney is one of Marohn’s personal heroes). The “suburban experiment,” as he calls it, has been a ﬁscal failure. On top of the issues of low-density tax collection, sprawling development is more expensive to build. Roads are wider and require more paving. Water and sewage service costs are higher. It costs more to maintain emergency services since more ﬁre stations and police stations are needed per capita to keep response times down. Children need to be bused farther distances to school. One study by the Denver Regional Council of Governments found that conventional suburban development would cost local governments $4.3 billion more in infrastructure costs than compact, “smart” growth through 2020, only counting capital construction costs for sewer, water, and road infrastructure. A 2008 report by the University of Utah’s Arthur C. Nelson estimated that municipal service costs in low-density, sprawling locations can be as much as 2.5 times those in compact, higher-density locations.

Marohn thinks this is all just too gluttonous. “The fact that I can drive to work on paved roads where I can drive ﬁfty-ﬁve miles an hour the minute I leave my driveway despite the fact that I won’t see another car for ﬁve miles,” he says, “is living beyond our means on a grand, grand scale.”

Marohn is one of a growing number of sprawl refugees I encountered during my reporting—people who at one point helped enable the building of modern-day suburbia but now spend their days lobbying against it with the zeal of religious converts. Some, like Marohn, focus on the unsustainability of the ﬁnancial structure. Others focus on the actual physical design of the suburbs and point to all the ways it’s ﬂawed. Most of them argue for the development of more walkable communities closer to public transportation. But their unifying criticism is that our spread-out development pattern was manufactured, packaged, and sold to Americans as part of an American Dream that fails to deliver on its promises.

Leigh Gallagher is an assistant managing editor at Fortune and a frequent guest on MSNBC’s Morning Joe, among other national television and radio news shows. She lives in New York City. This article is excerpted from Gallagher’s book, The End of the Suburbs, out now in paperback.

Contact us at letters@time.com.