During the housing bubble, Americans moved in droves to the exurbs, to newly paved subdivisions on what was once rural land. Far-out suburbs had some of the fastest population growth in the country in the early 2000s, fueled by cheap housing and easy mortgages. And these places helped redefine how we think about metropolitan areas like Washington, pushing their edges farther and farther from the traditional downtown.

In the wake of the housing crash, these same places took the biggest hit. Population growth in the exurbs stalled. They produced a new American phenomenon: the ghost subdivision of developments abandoned during the housing collapse before anyone got around to finishing the roads or sidewalks.

These scenes and demographic trends left the impression that maybe Americans had changed their minds about exurban living. New Census data, though, suggests that eight years after the housing crash, Americans are starting to move back there again.

The fledgling trend, captured in data through 2014, raises questions about whether American preferences for where and how to live truly changed much during the housing bust, or if we simply put our exurban aspirations on hold. At the same time, the shift calls into question a parallel and popular narrative: that Americans who once preferred the suburbs would now rather move into the city.

Demographic data over the last three years have tentatively supported this argument, with implications for the type of housing Americans want (smaller homes over large McMansions), the type of communities they prefer ("walkable" over car-dependent ones), and where developers should plan to build. The evidence: From 2011 until 2013, dense counties at the center of large metropolitan areas in the U.S. saw faster population growth than the exurbs, a fact cheered by city-lovers as a sign that urban living was on the rise again.

The updated Census county population estimates released Thursday, though, show that the exurbs are now again growing faster than more urban places, according to Brookings Institution demographer William Frey.

This shift — urban areas surpassing exurbs, then falling behind again — is illustrated by the blue and yellow lines above, using a classification developed several years ago by Brookings.

That picture doesn't mean that more Americans now live in exurbs than what Frey calls the "urban core," nor that cities are even shrinking. It means, rather, that the most urban counties are now growing more slowly than counties containing the far-out suburbs.

"It’s not going to be reverting back to the early part of 2000s when we had this maniac exurban and suburban growth," Frey predicts. But it does appear now that the last three years were atypical.

Demographers have been waiting for new data about migration patterns and population growth because our understanding of what Americans want for the last several years has been clouded by the weak economy. Did far-flung suburbs stop growing because fewer families wanted to live there, or because fewer families had the means to move (and fewer builders the demand to build)? Likewise, have people been staying in cities because they want to be there, or because they haven't been able to leave?

For the last several years, it's been difficult to untangle the economic story (people can't move to the suburbs) from the preference story (people don't want to).

"There are too many things happening at one time to be able to say 'that’s going to be the future,'" Frey says of the resurgence of cities. "I think a lot of this so-called 'return to the city' has a lot to do with people kind of being stuck in place because they can’t qualify for a mortgage, they can’t get a job, they're still paying tuition, they're living in their parents' basement. All of that is a time-specific, almost generation-specific phenomenon. It’s hard to pull that out and say this just means people are going to stay in the city."

From the start of the housing crash in 2006 until just the last few years, fewer people have been leaving the most urban counties as the steep yellow line here shows: Among the largest metropolitan areas in the country, the "urban core" lost more than 1.2 million net residents on the eve of the housing bust, a number that has shrunk considerably since then.

Now that trend appears to be reversing, too. Urban areas may still be growing despite the loss of residents to other parts of the country, thanks to foreign immigration and the natural population growth that occurs when people have children. Domestic migration, though, tells us something important about where people chose to move when they leave one part of the country for another.

Frey is still cautious about what these trends mean in the long run, in part because Americans are still moving at much lower rates than usual. During down times in the economy, we're more likely to stay put wherever we are because we're not moving for new jobs, or to buy new homes, or because many of us are putting off major life transitions like having a family or moving out on our own. This picture of where Americans want to move is also partly complicated by policies that make it easier for developers to build new — and cheaper — housing in the exurbs than in the heart of dense cities.

The question of whether Millennials in particular have changed their housing preferences — opting for cities over suburbs at higher rates than their parents did — will take a few more years to answer definitively. Young adults are only now starting to graduate from college into a world where they have more job options.

"We’ll have to wait until there's a generation of kids that come out that have opportunities to make decisions based on their preferences rather than just constraints," Frey says. "That’s not yet happened, either. It may be starting to happen."