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U.S. ZIP Codes Database 2026

Search by ZIP code, city, county, or state and find clear postal details with maps, time zones, and area code data.

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San Mateo County ZIP Codes

Browse all ZIP Codes, cities, and associated area codes registered in San Mateo County.

County State ZIP Code City Area Codes
San Mateo County CA 94019 Half Moon Bay 650
San Mateo County CA 94020 La Honda 650, 831
San Mateo County CA 94021 Loma Mar 650, 831
San Mateo County CA 94025 Menlo Park 650
San Mateo County CA 94026 Menlo Park 650
San Mateo County CA 94027 Atherton 650
San Mateo County CA 94028 Portola Valley 650
San Mateo County CA 94030 Millbrae 650
San Mateo County CA 94037 Montara 650
San Mateo County CA 94038 Moss Beach 650
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About U.S. ZIP Codes

ZIP codes are a United States Postal Service system introduced in 1963 to make mail routing more accurate and efficient. The standard format uses five digits, while ZIP+4 adds four more digits for a more precise delivery segment.

ZIP codes cover the United States, its territories, military mail routes, and other USPS delivery points. This directory organizes that data for practical lookup by ZIP code, city, county, and state.