1. Nantucket County, Mass.
Average income: $137,811
Let’s just say if all the old men in Nantucket kept all their cash in a bucket, they would need a lot of buckets. The island of Nantucket (along with the two smaller islands making up Nantucket County), located south of Cape Cod off the coast of Massachusetts, is an upscale vacation destination and summer colony. The entire island is an historic district, with many pre-Civil War structures as well as a cobblestone Main Street and the oldest functioning windmill in the country. Tommy Hilfiger, John Kerry and Teresa Heinz, and Jerry Stiller and Anne Meara all have summer homes on Nantucket.
See full story: America's 10 Richest Counties