(Bloomberg News) The gap between the haves and have-nots in the U.S. is being drawn along geographic lines, Census Bureau data shows.

The number of counties where median household income decreased is almost 10 times the number that saw an increase, according to a Bloomberg analysis of Census figures comparing an average of the years 2005-2009 with 2000. The government figures also showed a concentration of wealth and education in coastal states.

"The dispersion of income is larger than it's ever been," said Douglas Besharov, a professor at the University of Maryland's School of Public Policy. "There used to be a much wider spread of incomes within geographic areas than there is now. There's much more of a clumping together."

The Census Bureau data from the American Community Survey cover more than 670,000 communities, including cities, counties and neighborhoods, and represent about one in 10 U.S. households. The estimates, compiled from surveys conducted over five years on topics such as poverty, housing costs and commuting times, are the last look at the U.S. population before the Census Bureau releases figures from its 2010 decennial count on Dec. 21.

The Washington metropolitan area emerged as the wealthiest and most educated region of the past five years. The only three communities with median household incomes higher than $100,000 are in suburban counties in Virginia. Maryland, which also borders the nation's capital, saw income levels in Howard County increase at the eighth-fastest pace in the U.S. since 2000.

Washington Suburbs

The Washington suburbs are home to government contractors such as Bethesda, Md.-based Lockheed Martin Corp., the world's largest defense company, and General Dynamics Corp., the Falls Church, Va.-based maker of Abrams tanks and Gulfstream business jets.

The 10 communities with the highest incomes are located on the East Coast--Maryland, New Jersey, New York and Virginia--with the exception of Douglas County in Colorado. Among counties with median household incomes of less than $25,000, the bottom 10 are in Alabama, Arkansas, Georgia and Kentucky.

The government numbers indicated that the Spanish-speaking population declined in some border-state communities--Arizona, California, New Mexico and Texas--and gained in counties further north, in Virginia and North Carolina, compared with 2000 census data.

'Vibrant Economy'

"There's some evidence that in the nation as a whole the rise of immigration has leveled off or even gone down as the recession has hit," said D'Vera Cohn, a census analyst at the Pew Research Center in Washington. Northern Virginia has had a "vibrant economy" in recent years and that has attracted skilled foreign-born workers and others employed in the services industry, she said.

Seven of the 17 counties where more than half of residents 25 years or older had a college degree are located in the Washington suburbs, the Census Bureau said. Five of the counties are in landlocked states, according to data in the release of the American Community Survey.

"The ACS represents the first time such a massive compilation of data estimates for small geographic areas is available," Robert Groves, director of the Census Bureau, said yesterday in a statement. The "very important socioeconomic information will inform planners throughout the country," he said on a conference call with reporters.

College Graduates

The community with the lowest percentage of college graduates was Owsley County, Ky., where 4.6% of residents had a bachelor's degree. Falls Church in Virginia had the highest at 69.5%. Owsley also had the lowest median household income, at $18,869, and Loudoun County, Va., had the highest at $112,021.

Data from the final census count will affect the allocation of about $4 trillion in government funds during the next 10 years and determine which states will gain or lose seats in Congress.