The Washington D.C. area, including suburbs in Maryland and Virginia, are benefiting from a healthy job market in 2012, much of it linked to the federal government. Demand for homes is consistently strong, and foreclosure activity in the metropolitan area slowed in the first half of the year. (Ron Edmonds/AP)

The Washington region has emerged from the recession looking even more affluent compared with the rest of the country, boasting seven of the 10 counties with the highest household incomes in the nation, new census numbers show.

With a median household income surpassing $119,000, Loudoun County heads the list. Fairfax County, at nearly $106,000, is second. Both have held the same positions for several years running.

More surprising, Arlington County leapfrogged from the fifth spot to third, with a median household income of almost $101,000, a $6,000 gain in one year. Four in 10 households in the county are single person, leaving Arlington with a relatively small share of residents whose affluence comes from two incomes, compared with Loudoun and Fairfax.

Other counties in the top 10 are Howard, Prince William, Fauquier and Montgomery, which had dropped out of it in 2010. Among states, Maryland has the nation’s highest household income level, and Virginia is ninth.

The rankings in the 2011 American Community Survey released Thursday expand Washington’s dominance among high-income households, reflecting a regional economy that was largely cushioned as the recession yanked down income levels elsewhere. Household incomes rose in most counties around Washington last year, even as they continued to sink around the country.

The stability of an economy built on the pillars of the federal government, its legions of contractors and a flourishing high-tech sector is evident in the income rankings.

In 2007, before the recession began, five counties in suburban Washington made it into the top 10. By 2010, there were six. The seven in the latest ranking is an all-time high.

“It’s not only that we have low unemployment and a lot of dual-income households,” said Stephen Fuller, director of the Center for Regional Analysis at George Mason University. “We lost a few government jobs, but not the high-paying, professional business-service jobs that are still growing, if not as fast as they used to. Since the rest of the country is in such poor shape, we just have to show a little bit of growth here, and we look pretty good.”

While looming federal budget cuts could threaten the growth of Washington’s high-income households, the region is rife with the kind of residents that have thrived even in tough times.

The area has the nation’s highest level of adults with college degrees. It also is high in shares of households that have two incomes and married couples who postpone having children until they establish themselves professionally.

“A big sliver of American society that generally does well tends to cluster in Washington,” said William Frey, a demographer with the Brookings Institution. “When people make the argument that $250,000 is middle income, that’s way higher than most of the country regards as middle income. But here in Washington, your next-door neighbor has that kind of income.”

The census rankings are estimates based on incomes reported by a sample of people who receive the American Community Survey, which replaced the old long-form census questionnaire. The margins of error can be as high as 14.5 percentage points in a smaller county like Fauquier or as low as 2.5 percentage points in a large county like Fairfax.

But if the income figures are only approximate, the trend is clear.

The District, which the census compares to both states and counties, has seen its ranking shoot up in the last five years as its median household income has risen from $54,000 to about $63,000. When compared with states, it rose from 16th to fifth. Compared with counties, it ranks 125, up from 247.

The high household-income levels throughout the region reflect its success in attracting newcomers who work in private business, a growing sector of the economy, as well as the federal government.

“This is a result of the moves of the Northrop Grummans, the Hiltons, the Volkwagens, the ­SAICs,” said Jim Dinegar, head of the Washington Board of Trade, citing corporations that expanded their presence in Washington in recent years. “They provide high-paying, good jobs that bring more of these people to the area.”

Loudoun County, with its proximity to the high-tech corridor around Dulles International Airport, has watched its population soar over the past five years. Amid one of the nation’s worst recessions, its median household income declined for the first time this year, but only by $400, which is well within the margin of error.

Residents take pride in living in the most affluent county in the country, said Scott K. York (R), chairman of the Loudoun County Board of Supervisors.

“Every time it comes to the budget, everybody comes up and says it’s the wealthiest county, so we should fully fund the school budget,” he said. “We use it often when we try to recruit businesses to Loudoun County.”

With a broad level of affluence in so many places, many residents no longer notice it.

Gordon J. Bernhardt, president of the investment advisory firm Bernhardt Wealth Management in McLean, said he thinks San Diego and San Francisco feel richer.

“If you ask people if they’re affluent, they’ll say they’re not,” he said. “We’ve got some very successful people. They know they are successful. But they probably don’t define themselves as affluent.”

Wealth can introduce a whole new set of problems.

Lisa Sturtevant, a former Arlington County demographer now affiliated with the Center for Regional Analysis at George Mason, said one downside to having so many high-income residents is affordable housing becomes scarce. Arlington has lost residents earning less than $75,000, while gaining those earning more than $100,000.

Sturtevant, however, doesn’t live in Arlington County. She’s a resident of Alexandria, just across the county line.

“I couldn’t afford to live in Arlington,” she said.