“Cars are mostly unnecessary,” said a voice on the phone from Manhattan. “They’re dangerous and unsustainable, destroy public spaces, endanger citizens, and breed feelings of entitlement and tribalism. If we want to live in dense, healthy, inclusive cities, we need to reduce speed limits, stop building roads, and ban private car ownership. They spent 100 years trying to cram the car into the city, only to realize it was physically impossible. And when you try to do physically impossible things, you get some dysfunctional outcomes.”

For a moment, I wondered if I had the right number since I had arranged to interview a financial-trader-turned financier, and I don’t know too many Wall Street types who opine with such vehemence about the motorcar. But the man on the other end of the line assured me that I was speaking to the right person: sustainable-transportation advocate Mark Gorton.

“I never expected to become a sustainable-transportation advocate,” admitted Gorton, founder of OpenPlans, a nonprofit group dedicated to improving cities through technology, planning, and community engagement. OpenPlans is the legal entity behind open-source mapping software OpenGeo, public education news source GothamSchools, and multimedia transportation-advocacy projects Streetfilms and Streetsblog.

But before getting to know Gorton the advocate, it’s worth getting to know Gorton the businessman.

Gorton lives on the Upper West Side of Manhattan. At the Tribeca office he was calling me from, he spends his days immersed in the world of finance, math, and strategy. He holds multiple degrees, in engineering and business, from the likes of Harvard, Stanford, and Yale. He first gained pop-culture notoriety with his peer-to-peer file-sharing client LimeWire, a platform that had a large user-base until it was shut down in 2010 by a federal-court injunction. During this same time, Gorton was growing Tower Research Capital – which he founded after leaving Credit Suisse – into a company of 300 engineers, economists, mathematicians, and programmers, all focused on coming out on top in the risky business of high-frequency stock trading.

And Gorton the advocate? He emerged only after the businessman got fed up with his dangerous bicycle commute.

Gorton continued: “You would never swing a baseball bat two inches from someone’s face, but you have no problem driving two inches from them in a car going 30 miles per hour (48 kilometers per hour), which is way more dangerous. If you cycle around New York City, on the streets of Midtown, it doesn’t take too long before you’re almost killed a few times. And that really sensitizes you to how the streets are programmed. Our streets aren’t just a little wrong; they’re completely wrong.”

Gorton’s next move was to give me a history lesson about city streets. As Gorton sees it, the problem with city streets dates back to the Roaring Twenties, a period marked by sustained economic prosperity in many metropolitan centers, New York City included. Along with giving us some American literary classics, brooding expats of the Lost Generation – the generation that came of age during World War I – also gave us the US automobile industry, which immediately began mass-producing millions of private automobiles and letting them loose on our streets and roads. And with this automobile production came a glut of road construction projects.

By the time World War II came to an end, it had become clear that trying to squeeze countless motorcars onto the streets of rail-oriented cities had created a floor-space problem – one made worse by returning soldiers, who were crowded into a limited housing supply. Officials of the day responded with calls for a building boom, which, in turn, led to the prefabricated suburbia of the American Dream. New homes and new lives centered on daily use of the automobile.

Gorton explained that this freshly minted way of life was gradually cemented into the American psyche by relentless advertising campaigns from a booming car industry. “They were completely successful. This is the idea that came to dominate the United States, and the vast majority of cities followed this plan almost completely,” he said. “It basically drained the life out of the central cities.”

By the time a backlash finally organized – decades later – the fabric of American cities had been fundamentally altered, the car iconized into a symbol of status and freedom.

“Luckily,” said Gorton, “it wouldn’t last. This suburban dream is now a nightmare as people in the suburbs realize it’s not a very good life. You’re trapped in your car all day. As a parent, you have to shuttle your kids around everywhere because it’s not safe for them to walk or bike anywhere. There’s horrible traffic. It’s very sterile and boring.”

Gorton first turned anger into action in 1998. Rudy Giuliani was into his final term as mayor of New York City. Gorton remembers him as a man who was openly hostile to cycling, a man whose administration once considered banning bicycles from the Queensboro Bridge, linking Manhattan to Queens. By then, Gorton’s experiences of trying to stay alive in traffic had also connected him with Transportation Alternatives, a local group with cycling-advocacy roots reaching back to the 1970s. When Gorton realized that these like-minded advocates had a funding problem, he stepped in as strategist and financier.

“It’s hard to sit still and let it continue to suck when it’s so clear that there’s a better way out there,” he said with a laugh.

Gorton took to advocacy the way he took to business: with energy, skill, and a desire to come out on top. He started by getting his nonprofit group OpenPlans into producing films about the urban environment: streets, public spaces, and problem areas. These films later found a dedicated home online as Streetfilms (founded in 2007). In recent years, Streetfilms film crews have turned their lenses abroad, looking to import progressive transportation lessons: the Bus Rapid Transit system and Ciclovia celebrations of Bogotá, Colombia; the world’s biggest public bike-share in Hangzhou, China; the congestion pricing of London, England; and the covetable cycling mode share of Copenhagen, Denmark.

Gorton also became a speaker on transportation reform and hired an editor to find and produce content for what would become Streetsblog New York City (a website that attracts some 5,000 readers a day); for Streetsblog satellites in Los Angeles, San Francisco, Chicago, and the Capitol Hill neighborhood of Washington, DC; and for the Streetsblog Network, which curates news from more than 500 transportation blogs.

“There are a lot of people who hate traffic, who want their streets to be safe. But a lot of them feel really isolated,” he said. “You feel like a communist, or something like that, for saying you shouldn’t have an auto-dominated world.”

With a nod to his financial roots, Gorton often argues that multimodal transport options that combine cycling, walking, and transit are more fiscally sound than private cars. Speak to him long enough, and he’ll tell you that cars are also the culprits behind obesity, a misguided sense of entitlement, global warming, and urban collapse: obsolete machines to be exiled from most urban trips.

At one point, our discussion shifted from history and politics to philosophy, with Gorton’s stories of street battles often reminiscent of the tragedy of the commons. First explored in 1968 by ecologist Garrett Hardin in the journal Science, the tragedy of the commons refers to the long-term effects on parcels of land shared by individual herders in medieval Europe. Acting in his own self interest, each herder looked to maximize the number of cows grazing on the shared land – after all, each herder would receive the whole benefit of each extra cow while sharing the land’s overgrazing concerns among the entire group. Substitute cows for cars and overgrazing for congestion and collisions, and the comparison becomes a lot clearer.

This tragedy of the commons persists to this day. And this is exactly where Gorton finds hope for the livable city of the future.

“Even drivers hate traffic in their own neighborhood. So you can create a political dynamic where people fight to save their street. And you can win each of those 10,000 battles to make individual streets better,” he said. “The cities with the happiest transportation departments are in favor of killing the private car.”

Gorton told me that, slowly but surely, the status quo is changing.

He points to New York City’s current visionary commissioner at the Department of Transportation: Janette Sadik-Khan. Since 2008, Sadik-Khan has led the city’s Sustainable Streets strategy, implementing new bus routes, plazas, car-free events, and more than 280 miles (450 kilometers) of onstreet bike lanes. In Chicago, Mayor Rahm Emanuel has been building bike infrastructure with astonishing urgency, even quarreling with the Illinois government to let Chicago build protected bike lanes on roadways under state jurisdiction. This is all a part of Emanuel’s plan to bring 100 miles (160 kilometers) of protected lanes to Chicago by 2015. Even officials in Los Angeles are flirting with congestion pricing à la London, England, to make driving a less-desirable option.

Most importantly, Gorton told me, America’s young people are ignoring the private automobile like never before, buying fewer cars, and driving less thanks to flurries of other transportation options from transit authorities and car-sharing arrangements.

Gorton insists that even his bike rides around Manhattan have gotten safer: “One of the things I’ve learned is that it’s more terrifying than it’s dangerous. You actually can ride most of the time without dying. A big part of the secret is sticking to the handful of safe, protected bike routes out there.”

Luke Brocki is a freelance journalist based in Vancouver, Canada. His favorite way to get around town is on his rusty old 10-speed because it’s faster than walking, cheaper than driving, and more fun than squeezing through elbow-to-elbow transit crowds. @lukebrocki