The Maryland ZIP code that made the list at No. 68 is 21056, otherwise known as Gibson Island in Anne Arundel County. The median sale price for property on the private island is $1,643,750.

Boston's Back Bay is the only neighborhood to make the 10 most expensive ZIP codes that isn't in California or New York, coming in sixth with a $3.7 million median home price for the 02199 area ...