The Brief The most expensive ZIP code in the U.S. is 33109, Fisher Island in Miami Beach, with a median listing price of nearly $12 million. California dominates the top 10 list, with seven of the most expensive ZIP codes in the country. America's most expensive ZIP code was just revealed - and it apparently isn't in California. What we know:The most expensive ZIP code in the U.S. is 33109, Fisher Island in Miami Beach, according to a new analysis from Realtor.com. The Source: This information is based on a new analysis from Realtor.com, which evaluated median listing prices to identify the most expensive ZIP codes in the United States.