D.C. Suburbs Top List Of Richest Counties

For both health coverage and income, the national data reflect persistent gaps by race, ethnicity and geography. The median income for non-Hispanic whites last year was nearly $51,000, compared with about $36,000 for Latinos and nearly $31,000 for African Americans. Incomes were higher in the Northeast and the West than in the South and the Midwest.

The poverty rate in the Washington region was 7 percent last year -- the lowest among the nation's major metropolitan areas, according to the Census Bureau's American Community Survey, a separate set of census figures released yesterday. That survey shows that the District remains an area of relative poverty among its more affluent suburbs, although its poverty rate is not particularly extreme compared with other large U.S. cities.

The survey also suggests that the region's large, recent influx of immigrants has not particularly harmed its economic well-being. Area immigrants have a higher median income than immigrants in any other major metropolitan area -- including, as they do, an uncommon share of well-educated newcomers in government, technical and diplomatic jobs.

Basu, chairman of Sage Policy Group, an economic consulting firm in Baltimore, said the region's affluence was "decades in the making." During the 1990s, he said, suburban Maryland and Virginia emerged as hubs of information technology, biotechnology, and defense and aerospace work. And the high levels of spending since 2001 on defense and homeland security "have generated revenues for existing businesses and prompted business formation, job growth, income growth and investment."

Stephen S. Fuller, an economist at George Mason University, said the Washington area has ranked first in the nation in new jobs during the past five years.

The suburban prosperity has been brought about by people such as Tony Dawood, 46, of Leesburg, who moved to Loudoun County from Pennsylvania to take a job as a civil engineer. He is paid about $130,000 a year and augments his income with business investments.

"The affluence is overwhelming," Dawood said. His 17-year-old son has developed an interest in golf, an expensive hobby given the cost of $50 to $100 to play on a public course, and drives a new Mitsubishi Montero. It would be considered a nice car for a teenager, except that one of his friends has a brand-new Hummer and another drives a new Cadillac.

"They pull up in my driveway and my jaw drops," Dawood said.

Staff writers Susan Levine, Michael Alison Chandler and D'Vera Cohn contributed to this report.