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St. Mary's County Zip Codes



County State Zip Code City Area Codes
St. Mary's County MD 20630 Drayden 227, 240, 301
St. Mary's County MD 20634 Great Mills 227, 240, 301
St. Mary's County MD 20636 Hollywood 227, 240, 301, 410, 443, 667
St. Mary's County MD 20650 Leonardtown 227, 240, 301
St. Mary's County MD 20653 Lexington Park 227, 240, 301, 410, 443, 667
St. Mary's County MD 20656 Loveville 227, 240, 301
St. Mary's County MD 20659 Mechanicsville 227, 240, 301, 410, 443, 667
St. Mary's County MD 20660 Morganza 227, 240, 301
St. Mary's County MD 20667 Park Hall 227, 240, 301
St. Mary's County MD 20670 Patuxent River 227, 240, 301, 410, 443, 667
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Map of St. Mary's County


ZIP codes are a system of postal codes used by the United States Postal Service (USPS) since 1963. The term ZIP, an acronym for Zone Improvement Plan, is properly written in capital letters and was chosen to suggest that the mail travels more efficiently, and therefore more quickly, when senders use the code in the postal address. The basic format consists of five decimal numerical digits. An extended ZIP+4 code, introduced in the 1980s, includes the five digits of the ZIP code, a hyphen, and four more digits that determine a more precise location than the ZIP code alone. The term ZIP code was originally registered as a servicemark (a type of trademark) by the U.S. Postal Service, but its registration has since expired.


ZIP codes designate only delivery points within the United States and its dependencies, as well as locations of its armed forces. There are no ZIP codes reserved for designating mail bound for foreign destinations (with the exception of U.S. military units stationed outside of the United States), and therefore, international outbound mail should not include a ZIP code in the delivery address. The last line of a foreign address must only show the name of the country of destination.