Although the United States has been described as a "melting pot" for a century, American society has seldom lived up to that image. But a new study issued by the Brookings Institution indicates that not only is the nation becoming more of a melting pot, but that diversity is spreading.

Using the most recent data available from the U.S. Census Bureau, demographer William Frey determined that minority groups are settling outside of large metropolitan areas much more than they were at the time of 2000 Census

Frey says the Hispanic population, "which until very recently was heavily clustered in places like Los Angeles or Miami or Chicago or New York, are now really starting to spread out to other parts of the country."

That migration has shifted the population balance in nearly one third of all U.S. counties, where now, at least five percent of the residents are Hispanic.

"So a lot of suburban counties, a lot of exurban counties, that used to be all white are now getting new Hispanics and in some cases Asians and African Americans," Frey says. "And what this does is give much of America a first taste of what diversity is like."

William Frey says that traditionally minorities have tended to be less mobile than whites, settling in places where they had friends and family who provided support, but now they, too, are more likely to choose where they live based on economics.

"It has to do with lower cost of housing," he says. "It also has to do with the availability of jobs. Many of the jobs they are taking are jobs that require people with low skills, jobs in construction or services in retail. And the jobs are being created by people who moved there before, more middle-class folks."

Hispanics who are looking to fill those jobs are moving to cities like Las Vegas, Nevada; Phoenix, Arizona; and Orlando, Florida.

As for African Americans, they too, are looking for greater economic opportunity. Their grandparents and great-grandparents left rural areas in Mississippi, Alabama and Georgia for jobs in New York and Chicago, but they're returning to the South. And while Blacks have been moving to the south since the 1990s, William Frey says the most recent data indicate that trend has gotten stronger.

"Something like 72 percent of the nation's growth in the black population is taking place in the South," Frey says. "I think it has something to do with a cultural comfort zone. I think there is this long-term connection that African Americans feel with that region that they don't quite have with the other parts of the country."

The number one destination for African Americans in the South is Atlanta, Georgia, a city with a large black middle class.

Wherever there is economic growth in the country, the minority population is growing as well. It's a different story in much of the Midwest and mountain states, which are still predominantly white. Frey explains that in those areas, the population is aging.

"These tend to be places, the parts of the country, that aren't growing very fast," he says. "In other words, the people who live there are people who were left behind after a lot of other folks have moved to the fast growing sunbelt parts of the country. So they are getting older and whiter and the rest of the country is getting more diverse."

And that trend toward diversity in the rest of the country is likely to continue, according to Brookings Institution demographer William Frey. His report notes that in nearly one third of the nation's large metropolitan areas, minorities under age 15 outnumber their white counterparts.