4 Contra Costa ZIP Codes Among Nation's Priciest For 2023: Report

CONTRA COSTA COUNTY, CA — California continued to hold its position as the most expensive state in the United States for home buying, claiming 79 of the 100 most expensive ZIP codes in the country — including four in Contra Costa County —on a new report from PropertyShark.

To determine the nation's priciest ZIP codes, the real estate data firm considered all home transactions that closed between early January and late October.

PropertyShark said it "calculated median sale prices based on closed home sales, not asking prices, as we consider this methodology to provide the most accurate picture of actual market dynamics. Whereas asking prices reflect sellers' wishes, calculating medians based on sale prices reflects the transactional reality on the ground."

In contrast to the previous year — when most of the 100 most expensive U.S. ZIP codes saw price increases — 2023 witnessed a general decline in median sale prices. Specifically, this year, 70 of the 122 ZIP codes within the top 100 (due to 18 ties) experienced price drops, as compared to only 15 drops in the previous year.

Bay Area Remains Priciest Metro, But Loses 9 ZIPs Compared to 2022

The Bay Area continued to maintain its status as the most expensive metropolitan area in the United States with 37 of the priciest ZIP codes, according to Property Shark. However, there was a notable shift from the previous year as it lost nine ZIP codes compared to 2022, when it boasted 46.

Still, the Bay Area’s most expensive ZIP codes continued to be concentrated in Santa Clara County (16), followed by San Mateo (8), Marin (6), Contra Costa (4) and San Francisco (3) counties. Alameda County — which previously claimed three ZIP codes among the country’s most expensive — had no ZIPs in the top 100 this year.

Atherton's 94027 ZIP code kept its long-running crown as the nation's costliest, where the median sale price ballooned to $8.3 million this year. Marin County also landed in the top 10, where Stinson Beach's 94970 ZIP code tied for sixth place with a $4.5 million median sale price —a 27 percent leap from the year before.

In Contra Costa, Diablo's 94528 ZIP code was ranked the 42nd priciest with a $2.58 million median sale price, while Alamo's 94507 ZIP was the 43rd most expensive with a $2.57 million median price.

In a three-way tie for the 70th most expensive was Danville's 94506 ZIP code with a $2.1 million median price, along with 02493 in Weston Middlesex County, Massachusetts, and 07723 in Deal Monmouth County, New Jersey.

Coming in at No. 96, Orinda's 94563 ZIP code, which includes Orinda Country Club and a median price of $1.85 million, was in a four-way tie with the 92861 ZIP in Villa Park, Orange County, California, the 98004 ZIP in Bellevue, King County, Washington, and Santa Barbara's 93110 ZIP.

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