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
Maps and coordinates
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 20830 Olney Montgomery County 240
MD 20832 Olney Montgomery County 227, 240, 301
MD 20833 Brookeville Montgomery County 227, 240, 301, 410, 443, 667
MD 20837 Poolesville Montgomery County 227, 240, 301, 571, 703
MD 20838 Barnesville Montgomery County 227, 240, 301
MD 20839 Beallsville Montgomery County 227, 240, 301
MD 20841 Boyds Montgomery County 227, 240, 301
MD 20842 Dickerson Montgomery County 227, 240, 301, 571, 703
MD 20847 Rockville Montgomery County 240
MD 20848 Rockville Montgomery County 240
Page 17 of 63

Geographic Map of Maryland

Postal context

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.