Judged by household median income, Fairfax County is among the highest-income counties in the country, and was first on that list for many years.

Rockland also ranks 9th on the list of highest-income counties by median household income in the United States with $75,306 according to the 2000 census.

It is the 28th highest-income county in the United States with a median household income of $81,899.

The two counties have been trading places as the highest-income county in the United States in recent years.

Denali Borough is the 63rd highest-income county in the United States, by personal per capita income as of 2009.

It is the highest-income county in Pennsylvania and 24th highest in the nation as measured by median household income (as of 2010).

Mercer County ranks 80th among the highest-income counties in the United States.

Among the nation's 50 highest-income counties, only nine have death rates over 250 - two outside Atlanta and the rest outside New York.

The 2000 Census showed that the county ranked 63rd in the United States among the highest-income counties by median household.

King County ranks among the 100 highest-income counties in the United States.