Arlington’s median family income in 2012 was $137,216, putting the county comfortably in first place over the country’s second-richest county, Loudoun County (Va.), at $127,192.
Arlington’s median family income grew by more than $5,000 from 2011, up from $131,890.
Howard County (Md.), is the third-wealthiest county in America at $125,152, according to the Census Bureau, and Fairfax County (Va.) is fourth at $124,831.
Arlington’s income data does come with the caveat of a $10,561 margin of error, whereas Loudoun’s data has a $4,368 margin of error.
The census data differs from another commonly used ranking, median household income, which placed Arlington third in the nation, well behind Loudoun and Fairfax, based on 2011 data.