Move over, Westchester County. You, too, Marin County.

Those New York and California counties may have the reputation of being platinum-plated premises, home to America's most well-to-do. But according to the U.S. Census Bureau, they have been eclipsed among the nation's wealthiest counties by a surprising newcomer to the realm of the upper crust: Fauquier County.

The median household income in Fauquier increased to $67,990 in 2003, the Census Bureau reported last week in its Small Area Income and Poverty Estimates. That ranks Fauquier 32nd nationally, placing it in America's top 1 percent.

The county's median household income rose a modest 6.9 percent since 2000, when Fauquier ranked 55th nationally, but many counties that had ranked higher saw their figures decline by 2003. Median household income in Marin, a suburb of San Francisco, dropped 14.4 percent in the aftermath of the dot-com crash. Westchester, a New York City suburb, saw a decline of 3.7 percent.

Loudoun County ranked third nationally in the latest figures, down one spot from the 2000 ranking even though the county's median household income rose 6.1 percent, to $84,695.

Loudoun trails only Los Alamos, N.M., north of Albuquerque, and Douglas County, Colo., midway between Denver and Colorado Springs.

Despite the improving income numbers, both Loudoun and Fauquier saw a rise in a troubling statistic: the number of people in poverty.

Typically, the Census Bureau reported, as income levels rise, poverty rates fall. Yet in Loudoun, the percentage of residents in poverty soared by nearly a third -- from 2.8 percent of residents in 2000 to 3.7 percent in 2003.

In Fauquier, the poverty rate increased to 5.8 percent, up 7 percent from 2000's 5.4 percent. But now more than 7 percent of the county's children live in poverty, the census data show.

In Virginia, the median household income was $50,028, and the poverty rate was 9.9 percent, including 13.5 percent of children.