The long-awaited moment is here. The Millennials are on the move.

For the first time in almost a decade, America’s young adults are leaving home and forming their own households at a growing rate. The Millennial generation, now in their 20s and early 30s, have waited longer than any previous generation for this moment.

So, where will they go?

I remember the widespread optimism when I first left home in the mid-1980s. The country had spent the past century undergoing a great “regional income convergence,” with poor areas catching up to rich areas, until per-capita income was the most evenly distributed it had been in modern history. Everywhere I went, from New Jersey to Massachusetts to California to Washington DC, I found Americans of all income and skill levels living, working, and advancing together.

The Millennials face a very different America.

Since the 1980s, our cities and states have grown apart. The rich have gotten richer, and the rest have fallen behind. It used to be that these differences would drive people to move from the poorer areas to the richer ones, but not anymore. They can’t afford it.

Not everyone is worse off. A lawyer in a high-cost area like New York still winds up better off than if she lived in a low-cost area like the Deep South. As expensive as New York real estate is, it only takes about 20 percent of her paycheck. The janitor who cleans her office, however, is probably worse off. He’s paying over half his income for housing.

No wonder more people aren’t moving there.

So, where are they moving? According to the mortgage records at Realtor.com, the cities that top the list are Des Moines, Iowa; Provo, Utah; and Baton Rouge, Louisiana. In a word: Cheap.

There’s some evidence that they’re making a smart choice. Former Harvard Law School professor and current U.S. Senator Elizabeth Warren famously showed that middle-class families who tried to buy their way into wealthier neighborhoods with better schools had astonishingly high bankruptcy and foreclosure rates. Cheaper is safer.

But it’s not necessarily better. Cities with lower housing costs also tend to have lower wages, less productive firms, worse transportation infrastructure, more crime, more polluted air, underperforming schools, higher unemployment, fewer retail stores, and less entertainment.

Stanford economist Rebecca Diamond weighed these costs against the benefit of affordable housing, and she found that the lower-income workers who migrate to these cities wind up worse off than the higher-income workers who live in high-cost cities. As severe as income inequality has gotten, it actually understates the chasm between the two groups. The amenities are so much better in high-cost cities that they make inequality worse because so many lower-income workers can’t afford to move to these cities.

That’s the America that the Millennials face. (As an important side note, it is the America that many non-Millennials face too.  But that’s for another time.)

Most people don’t make high incomes straight out of college. They need good jobs in productive firms to climb the socioeconomic ladder. When I left college, those opportunities were more widely available than they are today. It didn’t take a generous inheritance or an onerous loan to find a good home in a high-wage city—and it still shouldn’t.

There are two obvious ways to address this problem. The first is to make housing affordable in high-wage, high-productivity cities. The second is to raise wages, improve school quality, rebuild infrastructure, and revitalize neighborhoods in low-wage, low-productivity cities.

There is no reason that we can’t do both at the same time.

Leaving home for the first time is one of the defining moments of life. It should be an exciting experience, full of possibility, as it was for most of my generation, and it should result in a new home where a new family can grow and prosper and thrive.

Whatever cities the Millennials choose, they will bring with them a welcome infusion of talent and taste all their own. Those assets deserve to be put to the best possible uses. We are still the land of opportunity, but we have to make those opportunities available to everyone, no matter where they live. In this challenge rests the fate of a generation.