It doesn't matter which superlative you pick: 25 Los Angeleses. 100 San Joses. 2,000 Poways. Nearly three Californias. That's how many people will be added to the United States population by the year 2050. They are not all going to live in Los Angeles, San Jose, or Poway, but a great many of them are going to live in California, thus pushing the state's population to about 60 million, according to the state Department of Finance.

In his latest book, The Next 100 Million: America in 2050, Los Angeles-based author and urbanist Joel Kotkin discuses who these 100 million new Americans are going to be, where they are going to live, and what type of lifestyles they will lead. They will, according to Kotkin, be more diverse than ever, but they will also drive familiar land use patterns by filling out suburban areas rather than flocking to larger, denser urban cores. CP&DR Editor Josh Stephens spoke with Kotkin about how these trends may play out in California. 

What proportion of America's 100 million more people are going to end up in California?

Migration to California is nothing like what it used to be, that's for sure.

The projections of California's population have been ratcheted down a bit in recent years. If you have a weak economy, if housing prices on the coast remain prohibitive, if you have a planning regime that makes it difficult to build single family homes, it's conceivable that people will go elsewhere. 

Are the state's planners and policy makers ready for that influx?

I think the planners to a large extent have been drinking the same Kool-Aid and they think they can force people to live in higher densities than they have generally wanted to do.  I think there's very little concern about the economic development aspects. Just like a lot of, if you will, "cowboy developers" built huge tracts but didn't think about jobs and amenities, you have planners who are thinking about design and amenities but aren't thinking about jobs.

I think there's a market for high-density. I don't think it's huge, and as the millennial generation gets older they will want a townhouse or single-family house, and if they can't find it in California they'll find it somewhere else like Texas.

Is it OK for California if people want to move to Texas?

If you already have your money and you're comfortable, having more people in California probably doesn't do much for your life. But if you're building a business and you depend on the migration of workers into your areas as part of your workforce, then it's probably a negative.

As somebody who came to California and always found it to be an exciting environment, I don't see the same excitement and same level of dynamism as I did 20-25 years ago. I hear my students talking about moving back to St. Louis or Texas. Maybe this is California going into its late middle age, and maybe that's just an evolutionary step. When I go to a place like Houston, Austin, or Dallas the upward trajectory is very strong.  In California, I don't feel that as much as I did before.

Is there a place for further density in urban cores?

There's certainly a place for it, but I think the market for the density was vastly exaggerated. If you look at the condo buildings that are in trouble or have gone rental, I would not exactly call it a great success.  There's a role for density, but it should be market-driven, not planning-driven.

It's the plain vanilla neighborhoods that are going to be the people who stay, who belong to the synagogues and churches, who are going to vote, who are going to live in that neighborhood for 20-30 years. A lot of the young people who live in the high-density housing are transitory. You're not going to build your community as much on those areas.

What places in California are you most optimistic about?

In the San Gabriel Valley the Arcadias and places like that are fascinating laboratories. And Ontario. What I like about Ontario is that is has the airport, transportation connections, a strong job market. It's the connecting point between LA County and the Inland Empire. I like Burbank. Downtown Burbank is in many ways livelier than downtown Los Angeles. You see people on the street and a mix of movie theaters and shops and restaurants, and it's really in a human-scale space.

Irvine has a very high percentage of its population living and working in the same area, and that's a direction we're going to have to go in to achieve sustainability with a growing population. The one thing we can do is try to get people to do more at home or close to home.

Which places are you most concerned about?

By far the biggest worries would be South LA, Oakland, and of course all the outer-ring suburbs: San Bernardino, Moreno Valley, the parts of the Central Valley that are close to the Bay Area but have an insufficient job base. If the Port of LA declines along with what's left of the industrial economy, those areas could be in serious trouble.

The Santa Monicas, San Franciscos, and Palo Altos of the world will do fine. They're attractive and have strong economic institutions. But Oakland is a very different story from San Francisco. People will pay for density in exchange for lots of amenities, but if there's not much amenity, then what's the point of the density?

As the state and its cities mature, what should the center cities do?  What should they do to avoid being just "luxury" cities?

I look at what LA could do, and the first and foremost thing is to improve the climate for entprenhurship and encourage poeple to start and grow companies. Right now, that's not happening. Our losses in Los Angeles County are much deeper than in most of the other urban areas of America.

We need to build up our infrastructure and have a much better economic climate. Our economy is getting weaker and weaker, so our ability to invest and build up is also weaker. Arnold and Villaraigsoa talk about green jobs, but to have green jobs you have to have jobs. You can't get people to retrofit their houses for energy savings when you don't have any money.

You're generally bullish on suburbs. Which suburban areas are going to have trouble as the population grows?

The ones that don't have jobs. The high unemployment in the Inland Empire is made up in part by people who used to work in LA and have lost their jobs. Places that have not generated economies to support their housing are really vulnerable.

How does diversity play out in California these next 40 years?

It's a real advantage. California is a leader in all the things you associate with diversity. There's been enormous growth both in Southern California and in Silicon Valley tied to immigrant networks from India and China, and also other countries like Israel. These are great strengths because those ethnic groups are probably willing to pay a little more and deal with a little more hassle to be in a place where there are cultural institutions, restaurants, and connections.

The immigrant economy is something we have and can build on. But you have to invest in skills education and infrastructure. And one thing is certain: many of those immigrants are going to want single-family homes. Take that out of the equation, and they're going to start looking elsewhere.

This interview has been edited and condensed.