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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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Boulder County ZIP Codes

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

County State ZIP Code City Area Codes
Boulder County CO 80025 Eldorado Springs 303, 720, 983
Boulder County CO 80026 Lafayette 303, 720, 983
Boulder County CO 80027 Louisville 303, 720, 983
Boulder County CO 80028 Louisville 303
Boulder County CO 80301 Boulder 303, 720, 983
Boulder County CO 80302 Boulder 303, 720, 983
Boulder County CO 80303 Boulder 303, 720, 983
Boulder County CO 80304 Boulder 303, 720, 983
Boulder County CO 80305 Boulder 303, 720, 983
Boulder County CO 80306 Boulder 303
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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.