For decades, Americans have been in love with the automobile — or so the saying goes. This single idea has been a central premise of transportation policy, pop culture and national history for 50 years. It animates how we think about designing the world around us, and how we talk about dissidents in our midst who dislike cars.

But is it accurate?

“This ‘love affair’ thesis is like the ultimate story,” said Peter Norton, a historian at the University of Virginia, who warns that we need to revisit how we came to believe this line before we embrace its logical conclusion in a future full of driverless cars.

“It’s one of the biggest public relations coups of all time,” he said. “It’s always treated as folk wisdom, as an organic growth from society. One of the signs of its success is that everyone forgets it was invented as a public relations campaign.”

This “love affair” was coined during a 1961 episode of a weekly television program called “The DuPont Show of the Week” (so called because it was sponsored by DuPont, which owned a 23 percent stake in General Motors at the time). The episode, titled “Merrily We Roll Along,” was promoted by DuPont as “the story of America’s love affair with the automobile.”

In it, Groucho Marx recounted that history to millions of Americans with a curious metaphor — the driver as the man and the car as the new girl in town (“Lizzie” was her name). Their “burning love affair” led to marriage, an extended honeymoon and, inevitably, a few challenges.

“We don’t always know how to get along with her, but you certainly can’t get along without her,” Marx concluded. “And if that isn’t marriage, I don’t know what is.”

The show aired at a time when cars were facing steep criticism. The new interstate highway system threatened to destroy or disrupt neighborhoods in many cities — a preponderance of them minority neighborhoods. A grass-roots group called the Emergency Committee on the Transportation Crisis was protesting “white men’s roads through black men’s homes.”

Routing the roads around neighborhoods meant having them go through parks and other green spaces, which also drew complaints.

The “love affair” story, Norton said, was a response to all this protest, and it successfully helped seed two ideas that have been entrenched ever since: that we’re bound to cars by something stronger than need, and that people who challenge that bond are turning up their noses at their fellow Americans.

“You can’t criticize love with logic,” Norton said. “Love is blind, love will find a way, love will do whatever it takes.”

In the half-century since then, we have largely rebuilt American communities to accommodate this love, retrofitting cities to make space for cars, bulldozing old buildings so that we can park them and constructing new communities where it’s not possible to get around without them.

This has evolved into a set of assumptions — Americans prefer cars to other forms of transportation, we’d rather have plentiful parking than bustling sidewalks, our roads should be reserved primarily for cars and not pedestrians — that we’ve inherited as we begin to envision a future where driverless cars might make us dependent on automobiles in new ways.

This isn’t to say that there aren’t people who love their cars. The phenomenon of sports cars, weekend cars and collector cars is real. So, too, is the allure for many people of road trips, scenic highways or weekend drives through the country.

What Norton disputes — and what he has written about in the book “Fighting Traffic: The Dawn of the Motor Age in the American City” — is that history shows that we’ve built car-dependent cities because that’s what Americans wanted. Not so, he says.

“When I actually looked into the history record, documents from the time, I found just the opposite,” Norton said. “What Americans in cities wanted in the ’20s was to get the cars out.”

Media at the time recount pedestrians ranting against the automobile as an intrusion and an undemocratic bully. Newspapers contained cartoons portraying rich drivers in luxury cars running over working-class kids. Three-quarters of traffic fatalities at the time were pedestrians.

“All of that history has been lost,” Norton said.

So, too, has the history of how the auto industry responded. In the mid-1920s, Norton said, the industry began a concerted effort to fundamentally recast the problem: Cars weren’t intruding on a public domain long freely used by pedestrians; pedestrians were wandering into roads that should be reserved for cars.

The auto industry effectively codified this idea in the crime of “jaywalking,” which remains with us today. The industry then offered to analyze local crash data for newspapers, which began in the mid-1920s to run stories increasingly blaming pedestrians for their plight. A traffic court magistrate writing in the New York Times in 1924 lamented that it was suddenly the fashion to blame “jaywalkers” for 70 to 90 percent of accidents, creating a “smoke screen” to conceal the harm of cars and to override the legal rights of pedestrians.

“As it stands, the motorist has won his contest for the use of the streets over the foot passengers, despite the present efforts of police, courts and motor vehicle authorities to regulate him and his kind,” wrote the magistrate, W. Bruce Cobb. “The motorist has inspired fear and the sort of respect that brute force inspires.”

Now, about 86 percent of Americans get to work every day in a private car — a statistic that’s often taken to mean that the vast majority of us choose to travel that way. Norton challenges that interpretation.

“I actually drive most of the way to work,” he admitted. “I do it because the choices stink.”

But even when we grumble about the misery of commuting in traffic, the culprit, invariably, isn’t the car itself — it’s the insufficient infrastructure that can’t quite contain it. It’s the highways that need widening, the roads that demand higher speed limits, the traffic lights that could use synchronizing.

Norton isn’t advocating nostalgia for pre-Model T America. He’s suggesting that, as we approach the era of the driverless car, we reconsider how we arrived at a world where cities are made in the image of parking lots.