Although millions of Americans spent just 10 minutes completing the 10 questions on the 2010 census form, demographer William H. Frey has been able to discern any number of trends from the answers.

One is that fewer people came here from other countries during the last decade than in the 1990s.

Still, those who come are landing in what he calls the "immigrant magnets" — New York, Los Angeles, Chicago, and San Francisco — where there are diverse opportunities for employment and communities of their own countrymen.

These cities are also the largest sources of "out-migration" to other areas of the country, yet the cities' populations, especially those of New York and Los Angeles, are growing as a result of continued foreign immigration and a high birthrate, he said.

The biggest pattern of movement from 2000 to 2010 was instead "in-migration," toward what Frey, senior fellow at the Brookings Institution, calls "the new Sunbelt" — encompassing states such as Virginia, the Carolinas, Oregon, and, oddly enough, Alaska.

"This is middle-class flight from more expensive states — the same reason why people moved into the suburbs," Frey told a session at the Philadelphia Fed's "Building Resilient Cities" conference at the Hyatt Regency Philadelphia Wednesday.

The minority populations of many of these states — mainly Hispanic and Asian — are also growing, "tagging along" with the wave of middle-class in-migrants, he said.

This movement is slowing, however, the likely result of the continued economic downturn since fall 2008.

Frey said 2010-11 brought "the lowest migration rate since the end of World War II."

Frey calls seven states, including New Jersey, the "Melting Pot," because of the substantial growth of their foreign-born populations.

"In these states, just 37 percent are native-born," Frey said. Among the Hispanic population, 72 percent speak Spanish at home. Sixty-five percent of the Asian population speaks a native tongue.

In New Jersey, 40 percent of those under 18 are members of a minority group, he said.

Other census trends Frey has identified:

Exurban growth has slowed, but city populations have declined less or even ticked up slightly.

Seventy-five percent of the population gain in the South was African American, primarily young professionals and retirees.

Suburbs remain 75 percent white, with a heavy concentration in the Midwestern states that appears to be aging in place.

Cities such as Philadelphia, Atlanta, and Pittsburgh are experiencing growth in aging baby boomers, but declines in the number of younger people. The 65-and-older population in the Philadelphia suburbs will grow faster than that of the city in the next 30 years because suburbanites will stay where they are.

Why is tracking population trends important?

For New York City, identifying an ever-changing population mix and movement among neighborhoods helps officials figure out where to target services, said Joseph Salvo, director of the population division of the city's planning department.

"There are 1.8 million people in New York City who have problems with English," Salvo said. "Forty-six percent of our workers are foreign-born. We want them to participate fully in the life of the city, so we need to know where to offer language courses."

Yet varying levels of education among non-English-speakers need to be taken into account as well, Salvo said.

"Six percent of Mexican immigrants are college-educated, as are 55 percent of Russians," he said. "There need to be different language programs developed."

A few years ago, members of a family from Africa died in a fire because they didn't know about smoke alarms. Public safety officials looked at the population data, Salvo said, and targeted areas where they could demonstrate the value of those alarms.

Contact Alan J. Heavens at 215-854-2472,, or follow @alheavens at Twitter.