For nearly a decade, the Silicon Valley enclave of Atherton reigned as the most expensive ZIP code in America. This year, it was dethroned — by a private island off the coast of Miami.
According to a new report from real estate data firm PropertyShark, Miami Beach’s Fisher Island (33109) claimed the nation’s top spot in 2025 with a median sale price of $9.5 million, a 65% jump from last year.
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That bump ended Atherton’s eight-year streak at No. 1, though the San Mateo County community still logged a record $8.33 million median, good for second place nationwide.
“Price trends were so vertical on Fisher Island this year that the cheapest home sold for $1.41 million, while the most expensive was bought for nearly $23.7 million,” PropertyShark reported.
Atherton, a small, largely residential town between Menlo Park and Redwood City, is defined by acre-plus lots and zoning that limits most parcels to a single home, keeping supply tight…