Photo by: Hugo E. Chaves

In Miami and other American cities, the conversation has changed from mitigating disaster to managing success. But there’s a lot to manage.

It wasn’t long ago that putting the prefix “urban-” before a word was like putting “-industrial complex” after it: Whatever the rest of the term was, it was going to be bad. Urban poverty was somehow worse than other poverty, urban crime scarier than the suburban or rural variety. Urban contemporary music was … well, you get the point.

As anyone trying to rent a New York City apartment will tell you, that’s changed. Cities have become much more appealing destinations. According to the Brookings Institution, from 2010-2012, the growth of population in America’s largest cities outpaced that of suburbs for the first time since the 1920s.

“Well, how the hell did that happen?” asks Carol Coletta, the Vice President of Community and National Initiatives at the John S. and James L. Knight Foundation. “That’s a sea change in America.”

Seriously. In fact, New York’s story over the past 10 to 15 years has been about trying to deal with the consequences of that sudden success amid the hangover from the bad years. Where’s the working class supposed to live when affluent people suddenly want apartments in Crown Heights, Bed-Stuy and Bushwick? Can aging transit infrastructure, often neglected during lean years, support a growing population?

There’s still plenty to worry about in cities, in other words, but the focus now is on figuring out how to manage a renaissance (and do so equitably) rather than how to trigger one.

That mix of challenge and potential is what Coletta says led to the creation of the Knight Cities Challenge, a $5 million fund that opens for applications today from anyone who has an idea of how to help cities keep attracting new people while expanding opportunity and improving civic engagement. (Full disclosure: A separate Knight fund helps support CityLimits.org.)

“There are things that we know are critical to the success of cities. It’s important to create opportunity. It’s important to attract the ‘best and brightest.’ And it’s important to build a culture of engagement,” Coletta says. The impetus for the fund is that, “We don’t know ways to do all that.”

While there’s been a lot of thinking and talking about cities in the past few years, not every thinker or talker has put a lot of emphasis on equity and opportunity. Mayor Bloomberg, for one, seemed to see growth as an unqualified good thing for the city. He built and preserved a lot of subsidized housing and incubated new, small-scale programs to fight poverty, but those conversations were separate from any discussion of whether the city’s boom had winners and losers.

By contrast, the connections among affordability, development and engagement were central to the critique Bill de Blasio rode to City Hall. Skeptics wonder, however, whether the forces driving social inequality—globalization, technological change, et cetera—are too big for cities to actually mitigate.

That concern would apply to any city, big or small. But Coletta doesn’t share it.

“It’s just the opposite,” she says. “I think the city is probably the only unit of government at which people can really self-determine, and see a difference. If you consider the fact that livability has become a competitive advantage, that says to me that cities are far more in control of their fates than, let’s say, even a state. So I would suggest people have a rare opportunity to influence the future by working in cities.”

Knight stresses that it wants ideas from “activists, designers, artists, planning professionals, hackers, architects, city officials, educators, non-profits, entrepreneurs, block captains, social workers” and not just mayors or managers. Its application asks merely for a description of the idea, how it will help and what you’ll learn from trying it.

The catch is the idea has to be implemented in one of the 26 Knight communities, which include Detroit, Miami, Philadelphia, San Jose, Lexington, Ky., and others. But you can submit a general idea and, if it wins, Knight will set you up with a city to try it in.