U.S. postal lookup

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.

42,735 verified records
All states and U.S. territories
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State directory

Maryland ZIP Codes

Complete postal directory, details, and geographic map for the State of Maryland.

State ZIP Code City County Area Codes
MD 21757 Keymar Frederick County 227, 240, 301, 410, 443, 667
MD 21758 Knoxville Frederick County 227, 240, 301, 304, 540, 681, 826
MD 21759 Ladiesburg Frederick County 240
MD 21762 Libertytown Frederick County 227, 240, 301
MD 21765 Lisbon Howard County 410
MD 21766 Little Orleans Allegany County 227, 240, 301, 304, 681
MD 21767 Maugansville Washington County 227, 240, 301
MD 21769 Middletown Frederick County 227, 240, 301
MD 21770 Monrovia Frederick County 227, 240, 301
MD 21771 Mount Airy Frederick County 227, 240, 301, 410, 443, 667
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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.