It used to seem shocking that five of the ten richest counties in the United States were part of the DC Metropolitan Statistical Area, but the 2011 American Community Survey numbers released yesterday show that the DC suburbs now account for seven of the ten richest counties in America.
Loudon, Fairfax, and Arlington in Virginia lead the way followed by Hunterdon County, NJ then Howard County in Maryland; Somerset, NJ; Prince William and Fauquier in Virginia; Douglas, CO; and Montgomery County, MD.
Some caution is always warranted in interpreting these statistics, since county-level median income really measures a mix of affluence and success at zoning out poor people. Manhattan has more and richer rich people than Fairfax County, but also includes plenty of public housing and other policies specifically aimed at keeping some lower income families around. The extreme prosperity of Northern Virginia is a blend of high incomes and exclusionary zoning. Still this represents a remarkable transformation of America's urban geography.
The simple explanation is that we've gone corrupt and decadent, and as the vitality of the American empire declines its capital grows more splendid. The more sophisticated explanation, offered by David Leonhardt in August, is that the DC area is affluent for the same reason the other affluent parts of America are affluent—a very high share of the population has college degrees. But that in some ways only pushes the question back a further step. All these college graduates didn't end up in DC by coincidence. Rather, the national economy has transformed in such a way as to encourage large numbers of educated people to move here in search of work or because you accepted a job offer. Now some of that change has nothing in particular to do with political dysfunction. The journalism labor market that I work in, for example, has become more DC-centric because the Internet has led to a decline in regional newspapering and thus more geographical centralization of work opportunities in New York and Washington. That's not unrelated to the fact that the Capitol is here, but the change is a change in the technology of news distribution not a change in the working of the American political system.
But it seems a little implausible to avoid the conclusion that on the whole the American economy has gotten more deeply invested in influence-peddling—broadly construed—and that this is driving the Washington area to the top of the charts.