The San Mateo County city of Atherton took the no. 1 spot for the fourth year in a row.
The city has an average income of $525,000 per year -- which makes a half-million dollar salary below average for the area.
Hillsborough ranked third on the list and Los Altos Hills took the no. 5 spot.
Both of those cities have an average income upward of $400,000.
Check out the full list of Bloomberg's richest cities in America here.