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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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Frederick County ZIP Codes

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

County State ZIP Code City Area Codes
Frederick County MD 21718 Burkittsville 227, 240, 301
Frederick County MD 21727 Emmitsburg 227, 240, 301, 410, 443, 667
Frederick County MD 21754 Ijamsville 227, 240, 301
Frederick County MD 21755 Jefferson 227, 240, 301, 540, 571, 703, 826
Frederick County MD 21757 Keymar 227, 240, 301, 410, 443, 667
Frederick County MD 21758 Knoxville 227, 240, 301, 304, 540, 681, 826
Frederick County MD 21759 Ladiesburg 240
Frederick County MD 21762 Libertytown 227, 240, 301
Frederick County MD 21769 Middletown 227, 240, 301
Frederick County MD 21770 Monrovia 227, 240, 301
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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.