In Loudoun County, they have something called mansion subdivisions. Loudoun has been topping national wealth lists since 2006. (TRACY A WOODWARD/The Washington Post)

The Post reported Thursday on its front page that median household incomes in the area, particularly in Fairfax County, had declined in 2010. But it seemed to show continued gains for both Loudoun and Prince William, as the numbers assembled by Carol Morello and Ted Mellnik show:

Alexandria: $77,793 median household income; down $575

Arlington: $94,986; down $2,820 from 2009

Fairfax: $103, 010;down $1,181

Loudoun: $119,540; up $3,451

Prince William: $92,655, up $1,388.

Note that the amount of change over 2009 is often within the margin of error for the model-based estimates by the American Community Survey, so changes of less than $4,000 in a year are seen as statistically insignificant.

After the top three, Hunterdon County, N.J. is fourth, and Arlington is fifth. Stafford County, just outside the rigorous boundaries of the State of NoVa is seventh, at $94,317. Prince William is ninth. Montgomery County, Md., is 12th. Alexandria is 39th.

If you missed it, The Post’s Petula Dvorak ventured out to Manassas to glimpse Prince William’s newfound prosperity, and her column is here. But she also noted that 10 percent of the county’s homes went into foreclosure between 2004 and 2009. Also, a chart in USA Today in February revealed that 47.4 percent of Prince William homeowners owed more on their homes than they were worth, also called “underwater.” So there is some pain beneath the growth.