Arlington has become the place to live, if you’re a millennial, reports Patricia Sullivan for the Washington Post. Census numbers show that young adults between 25 and 34 years of age make up more than a fourth of the city’s population.

What draws them to Arlington? There’s the luxury apartments, millennial-friendly Whole Foods, the city’s “yoga boom,” its plethora of local bars and restaurants. There’s also an abundance of trails and easy metro access into D.C. But as the millennials grow up and start having babies, all the consumer goods that drew them to Arlington may not be enough to keep them there:

As millennials have children, their priorities expand to include good schools and family-friendly neighborhoods. A condo or townhouse can suddenly seem too small, and a bigger place in the same neighborhood may be too pricey.

Six in 10 surveyed Arlington residents between the ages of 25 to 34 told the county’s affordable-housing study group last year that it’s somewhat likely or very likely that they will move out of the county within five years because of housing costs.

… Historically, young adults have moved into Arlington starting around age 20 and left for other suburbs in large numbers once they reach their early 30s.

… Elizabeth Hardy, Arlington’s planner and demographer, said the county is planning a study of whether the out-migration of Arlington’s 30-somethings will continue. “Once we have an understanding of the factors that cause people to come or go, we could address how to keep them here,” she said.

This is a dilemma that the entire D.C. metro area seems to struggle with. The city is known for being transitory, a place whose political nature encourages a sort of temporary atmosphere. People come and go, and it’s difficult for any distinct culture to develop around anything excepting politics. Young people, especially, tend to migrate out of the city once they begin to develop a desire for roots. And who can blame them? Not only is housing exorbitantly expensive in the metro area—it is also difficult to build community in a place where people are so often moving and rootless.

Alexandria is perhaps one well-known exception to this rule: its history, rich local community, and vibrant urban fabric has helped to keep a distinctive—and permanent—culture alive. It is the second most millennial-populated city in the metro area, according to Sullivan’s article, yet it also boasts a diverse array of ages and ethnicities. The millennials I know who’ve come to Alexandria are determined to stay, if they can. Yet they face the same housing prices, the same tight-space issues, that those in Arlington face. What convinces them to stay?

The main difference between Alexandria and Arlington seems to be that the former has developed a community of stickers: people who love Alexandria for its own sake, and stay if it is at all in their power to do so. They’ll deal with the cramped spaces and high costs, because they love the city and believe it is a neighborhood and community worth treasuring.

Arlington, however, has developed a culture of boomers: people who circulate according to the jobs available, housing costs, and their time of life. While that isn’t necessarily bad in the short-term, it does create long-term consequences—it means that while Alexandria has rich local traditions and a strong fabric of community, Arlington struggles to develop these things. Its “culture” is a bit more commercial, reliant on trends and fashions. It’s built itself into a different sort of community hub, but it’s one almost exclusively for singles and young couples.

The difference between the two cities may also stem from the fact that Arlington is a bit more sprawling, without a defined historic center that draws community and commerce in the way Alexandria does. The heart of Alexandria still seems to draw people together: it’s not just a place for tourists, but also a hub for arts and commerce, community events and family outings. This helps people connect in a meaningful and lasting fashion. But Arlington’s downtown mainly consists of commercial areas: Clarendon, Courthouse, Rosslyn, as well as Pentagon City and Crystal City. These areas offer a variety of shops, restaurants, bakeries, a couple bookstores, some nice parks—but they are also populated with traffic-laden roads, imposing glass and concrete buildings, sterile sidewalks. They aren’t necessarily beautiful, walkable, or quiet, in the way Alexandria is.

It’s worth considering how to make the millennials stay in Arlington: both for the millennials’ sakes, and for Arlington’s. It is difficult to build a lasting community when you constantly have to uproot yourself and move to a more affordable place—and if that place is the suburbs, it may present other difficulties for these young people, as well. Meanwhile, cities like Arlington need to figure out ways to build this rich heritage and community fabric: it develops their commerce, gives them a more vibrant local culture, encourages a more diverse and connected populace. These are the sorts of things that help a city last.