Over the next 25 years, 78 million baby-boomers will retire to thriving metropolitan areas throughout the South and West. Meanwhile, new immigrants to the U.S. will concentrate in a few gateway cities, according to demographers William Frey and Ross DeVol of the Milken Institute in California.

Retirees will populate mostly white "heartland regions" and immigrants will create "multiple melting pots" in such cities as Los Angeles, San Francisco, New York, Washington, Houston, Dallas, Chicago and Miami -- resulting in sharp regional differences in U.S. society.

Melting pots are metropolitan areas where at least two minority groups have a greater representation in the population than their national average and where white residents are underrepresented.

• Only Dallas ranked in the top 10 metropolitan areas both for drawing immigrants and people from the rest of the country.

• California will continue diverging from the rest of the West -- so that by 2025, only one California child in four will be a non-Hispanic white.

• By contrast, eight in every 10 Utah children will be non-Hispanic whites.

Source: William H. Frey and Ross DeVol, "America's Demography in the New Century: Aging Baby Boomers and New Immigrants as Major Players," Policy Brief, March 9, 2000, Milken Institute; Paul Overberg, "Boomers to Retire Where They Work," USA Today, March 9, 2000.