One way to revive America’s cities may be to adapt to increasing densities in Americans suburbs:

But this analysis also misses something important. These trends don’t just represent people’s moving decisions — they also represent changes in the places themselves. If enough people move to a low-density area, it becomes a high-density area.

People are pouring into Dallas and San Diego. So unless those cities continue to sprawl ever farther out across the countryside, the new arrivals will increase density. People will want to live close to their jobs instead of enduring hour-long commutes. Apartment blocks will spring up where once-empty fields or single-family homes stood. Today’s fast-growing suburb is tomorrow’s urban area.

In other words, the great urban revival might not be ending, it might just be relocating. Instead of piling into existing cores, Americans might simply be creating new ones across the country. And if each of these new cities creates the productivity advantages enjoyed by places like San Francisco and New York City, this could be a good thing for the economy.

This is an intriguing concept: some suburbs, because of their popularity, willingness to build taller structures, and population size, might become like cities. This has already happened to some degree in a number of suburbs across the country.

Yet, just because a location has a certain number of people or reaches certain population densities does not necessarily mean that it feels or operates like a city. We also already have some denser urban areas – see the Los Angeles suburbs which are pretty dense compared to many metropolitan areas – but that does not automatically make them cities or urban. What is required? Most American cities have: a core or multiple cores that are multi-use and include a good number of businesses or offices; a walkability that extends for a good distance (beyond just a suburban downtown or large shopping center) and mass transit options to extend beyond the core(s) – in other words, good options beyond operating a car; a vibrancy and diversity that could range from thriving economic activity to restaurants and bars to filled public spaces; and an identity among residents and others that the area is a city.

Imagine Naperville, Illinois really wanted to become a city. It starts approving dense residential and commercial projects throughout the community. (Just to note: the local government has rejected these in the past.) The population ticks upward past 200,000 or even 300,000. There are still some pockets of single-family homes and vestiges of small-town life. How long would it take for the conditions of a city as discussed above arise? How would the community adapt to having so many businesses along I-88 rather than downtown? Would this limit the number of people who ride into Chicago on the Metra each day? (Naperville right now has the busiest stops in the whole system.) How would a city atmosphere develop? This all would take significant time and effort and perhaps decades before Naperville would be considered from both the inside and outside a city.