The findings are based on a CNBC.com analysis of Census Bureau numbers on average annual household income from 2006-2011 and results from Tuesday's elections.

The 10 richest counties accounted for 1,337,700 votes, or about 1.1 percent of the national popular vote.



In the richest, Massachusetts' Nantucket County, where average annual household income is over $137,000, Obama won by 63 percent to Romney's 36 percent with all precincts reporting. The richest county in Romney's home state is also where, just prior to accepting the Republican nomination, the former Massachusetts governor held a $75,000-per-person dinner fundraiser.

In none of the richest counties was the margin of victory wider than in California's Marin County, just north of San Francisco, where the president won by 74 percent to 23 percent, with all precincts reporting. In Marin, the average annual household income is $128,544.

The two richest counties where Romney won were in New Jersey: adjacent Hunterdon and Morris counties in the northern part of the state. Romney won in Morris by 55 percent to 44 percent and in Hunterdon by 59 percent to 40 percent. However, Somerset County, which abuts Hunterdon and Morris, went to Obama by 53 percent to 47 percent.

—By CNBC's Paul Toscano