Fairfax County is ranked #2 in a SmartAsset study showing the top 10 Virginia counties with the highest net worths.
Despite having the highest per capita income on the list, Loudoun County came in only at #7 due to also carrying a significantly higher per capita debt burden, also the highest on the list.
Poquoson County in the Tidewater area took the top spot on the list, due to its favorable per capita income vs. per capita debt burden ratio.
For the SmartAsset study, the firm calculated the ratio of net worth to per capita income for every county. This number can serve as insight into how much people have saved or invested relative to their income level. SmartAsset also calculated the ratio of net worth to debt per capita for each county. This measure incorporates a view of a county's debt burden relative to its overall net worth.
Lastly, they indexed each factor and calculated an overall index by taking a weighted average of each of these indices. The net worth to income index was given a weight of two and the net worth to debt index was given a weight of one.
Sources: U.S. Census Bureau 2016 American Community Survey, ESRI, Federal Reserve Bank of New York