In the following interview, we speak with Jeff Speck, author of Walkable City: How Downtown Can Save America, One Step at a Time. Speck is an architect and city planner in Washington, D.C., oversaw the Mayors' Institute on City Design, and served on the Sustainability Task Force of the Department of Homeland Security.

Speck argues that the concerns of young parents leaving urban centers in search of better schools for their children is, in a sense, a "good problem" for a city to have. Many cities are still working to attract those populations in the first place; school issues will come later.

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Audience Member: A lot of Fools have young children, and you mentioned that you have young children. I don't, but one day perhaps I would like to. There's sort of a running joke, "When do you move out of the city?" It's when your oldest child turns 5.

Jeff Speck: It's actually not that. It's 3, because we now have universal preschool in D.C., and people are moving out because they don't like the quality of the 3-year-old programs.

Audience Member: Right. So in a city like D.C., where the public schools are not known for being excellent -- which is putting it mildly, unfortunately -- how can millennials who right now are childless stay in the city?

Because right now you talk about this big demographic shift, that millennials and their baby boomer parents, who are empty nesters, are moving into the cities. What happens when the younger part of that cohort starts having their own children?

Speck: My wife and I have a 2-year-old and a 4-year-old. We had our house on the market, briefly -- the house that I built myself and didn't want to leave -- because we were facing this exact problem. We hit the lottery. We got lucky, like a lot of people do, but probably the minority, and our oldest child got into a charter school that we like, which means our younger child is also in that charter school.

My wife is quite active. Her name is Alice Speck, and she tweets a lot on education issues in the District. By the way, I am JeffSpeckAICP, like American Institute of Certified Planners, if you want to follow me on Twitter. I tweet a lot too.

My wife is very active in the education discussion, and every conversation I have like this in the city, or with her, the concept of education is brought up. Everyone has to deal with it their own way, but the simple fact is that it will remain the challenge for a long time. I think D.C. is getting better and better. Other cities are doing yet better than D.C. is doing. Of course, not every Fool is in D.C.

I hate to push back, but I think that, for most of my clients' cities, it's the wrong question to be asking, immediately, because they wish they had the millennial population that is worried about schools, that is ready to be worried about schools in the future, but in fact they have so few residents downtown and so little walkability downtown because of that absence of residents, that they're not yet at that step.

As planners, as philosophers, as people who think, we all believe and say and understand that the best cities, the ideal cities, are those which house everyone well, and how can you have a great city that doesn't have all kinds of people in it?

David Burns says, "Design a city that serves our kids, and I'll show you a city that serves everyone," etc., etc.

It's all well and good, but I remind myself that I lived for a decade, perfectly happily, in South Beach, in Miami, where I would go for months without a single stroller sighting. This was a city that didn't seem to contain anyone between 35 and 55, and certainly no kids, and it was a thriving, healthy city that had come back from being -- if any of you have seen Scarface -- come back from being a complete pit.

Without Al Pacino, many American cities are still in a condition similar to that. They need to provide those things that will attract the millennials and attract the empty nesters, and get to that point where a school problem becomes that good problem to have.

I'm less focused, these days, on the school issue than I am on not how cities can serve everyone, but how they can thrive. What you do see is the schools tend to come around 10 to 15 years later, but that's a long time to wait. We punish the pioneers.