When author and historian Joel Kotkin travels around the U.S. in his role as a consultant to city planners, he hears his clients repeat the same misconceptions again and again. He calls them urban legends.

“The one you hear most often is, ‘Cities are on the rebound! People are moving back to the cities!’ ” he says. “It takes different forms. The latest one I’m hearing is: ‘Empty nesters are flocking back to the cities!’ “

There’s a problem with legends, of course. They’re not true. And so it is with the urban legends Kotkin keeps hearing.

Consider those empty nesters – parents whose children have grown up and moved out. No matter how much civic boosters may wish it to be true, this affluent and highly desirable demographic is not returning to live in U.S. downtowns.

“If anything, the data show just the opposite,” Kotkin says. “If empty nesters decide to sell the family house in the suburbs, they move to a condo – in the suburbs. Or they move to the Sun Belt – to a suburb.”

The same goes for one urban legend after another, those little fairy tales that urban planners tell to convince themselves that cities are making a comeback.

Urbs versus Burbs

Is it true, for example, that gentrification is inspiring companies to put their headquarters in cities? Is it true that cities can cultivate a vibrant and viable civic culture without middle-class families? Is it true that most companies require an urban setting to do business in?

The answers, says Kotkin, are: No, no, and probably not. An urban setting, he concedes, just might help you do business, depending on what business you’re in.

“I suppose some kind of companies need to be in a city,” he says. “Bail bondsmen need to be near the courthouse. But that’s about it.”

You can understand why city managers, urban planners and “metropolitan elites” repeat the urban legends, mostly to one another. They’re deflecting an uncomfortable truth.

And the truth is that in the great struggle between cities and suburbs, raging now for a century or more, the verdict is finally in: Cities lost. The vast majority of people prefer the “burbs.” The long-predicted comeback of the traditional city isn’t in the cards.

‘Dream World’

For those of us who love cities, it’s hard to believe that the future of civilized life lies in the suburbs. You call that civilized?

“Metropolitan elites live in a dream world,” Kotkin says. “If 1,000 people move into lower downtown Denver in the last year, the elites think it’s a trend: stories in the newspaper, panel discussions, general celebration. Meanwhile, 10,000 people leave the city for the suburbs, and the elites ignore it.”

Traditional U.S. cities stopped growing 50 years ago and are now shrinking. Since 1950, almost all the growth in U.S. metropolitan areas has been beyond the city limits, in suburbs – sprawl, in a word.

And the trend seems to be accelerating. Census data released earlier this month show that during the 1990s, one city after another lost population, even as the counties surrounding them grew. In Ohio, for example, Cincinnati’s Hamilton County shrunk by 2.4%. Neighboring Boone County, in Kentucky, grew 49.3%. Even farther out from the city, Grant County, Kentucky, grew by 42.2%. From Washington to Cleveland to Denver, the trend was the same.

Hip and Cool

There are lots of obvious reasons for the cities’ decline – the decentralizing effects of telecommunications, the loss of manufacturing jobs, the inconveniences of public transit – but Kotkin is more appalled by the steps urban planners take in hopes of reversing the decline.

“They think they can revive their cities if they make them ‘hip and cool,’ ” he says, referring to the street festivals, cafes, arts fairs, high-end boutiques and other yuppie delights that attract the young and single, the childless and rich.

“But that’s not how cities last,” he says. “You can’t build a long-term civic culture around transient populations.”

What any healthy city requires is a stable base of middle-class families. But the conditions necessary for attracting and keeping families are precisely what city planners ignore.

“They’ve forgotten the basics,” Kotkin says. “Are the schools good? Are the streets clean and safe? It’s a lot easier to satisfy the yuppies with no kids than to fix the schools.” And so city life, once the backbone of civilized social arrangements, devolves into just another “niche lifestyle.”

Mixed Evidence

But can suburbs perform the essential functions of acculturation and community-building that cities once did? It’s a question Kotkin explores in his latest book, “The City: A Global History,” and he says the evidence for now is mixed.

Kotkin calls most of suburbia “slurbs,” vast stretches of undistinguished space choked with traffic and lined with commercial strips lacking character, charm, or – most important of all – a sense of civic identity that can bind their residents together.

On the other hand, some suburbs now reflect the influence of the new urbanists, planners who favor suburbs with walkable downtowns, open space and accessible cultural institutions.

‘Not in the Cities’

Even so, for many of us, the suburbs will require a lot of getting used to. What’s to happen to those “hip and cool” city- lovers who, over the next generation, may be pulled to the suburbs by professional necessity, as the social and economic center of gravity continues to shift?

At Southern California Institute of Architecture, where Kotkin teaches, he says, “I hear my students talk about all the great projects they’re going to do in cities after they graduate. And I have to tell them: Wait a minute. You’re architects and designers and urban planners. Where do you think you’re going to be working in the 21st century? Sorry, but it’s not in the cities.”

He says they look at him, disbelieving and horrified. They have seen the future. And it’s the suburbs. As for Kotkin, he was born in New York City and now lives in a suburb of Los Angeles.

Mr. Ferguson is a columnist for Bloomberg News.