The Census Bureau has confirmed that, once again, the Washington region dominates the list of the most affluent counties in the United States.

Among more than 3,000 counties nationwide, Loudoun County had the highest median household income last year, almost $119,000, according to Census Bureau data released Thursday.

Los Alamos County in New Mexico was next, followed by Maryland’s Howard County and Virginia’s Fairfax County. Hunterdon County in New Jersey completed the top five, but Virginia’s Arlington and Stafford counties made it into the top 10.

The Census Bureau ranked the city of Falls Church, with a median income of $121,000, as the richest U.S. county. But that’s because the bureau ranks Virginia’s independent cities with the nation’s counties.

Montgomery County and Prince William County did not miss the top 10 by much, and the top 30 included Charles, Calvert, Anne Arundel and St. Mary’s counties in Maryland, and the city of Fairfax in Virginia.

The Washington area has reigned over the list of most affluent counties for years, in large part because it has so many residents with college degrees and professional jobs. That gives the region a disproportionately large share of households in which two adults have well-paying jobs.

Here’s the Census Bureau list of counties with the highest median incomes:

Falls Church City, Va., $121,250

Loudoun County, Va., $118,934

Los Alamos County, N.M., $112,115

Howard County, Md., $108,234

Fairfax County, Va., $106,690

Hunterdon County, N.J., $103,301

Arlington County, Va., $99,255

Douglas County, Colo., $98,426

Stafford County, Va., $95,927

Somerset County, N.J., $95,574

Morris County, N.J., $95,236

Montgomery County, Md., $94,365

Prince William County, Va. $93,011

At the other end of the scale, the poorest county is Wilcox County, Ala., with a median household income of barely $22,000, the Census Bureau says. No county in Maryland or Virginia is among the bottom-ranked counties.