21742 -- U.S. ZIP code Municipality (1990): HAGERSTOWN, Maryland All ZIPs for this municipality (1990): 21740 21742 Population (2000): 25053 Housing Units (2000): 10541 Land area (2000): 48.920597 sq. miles (126.703758 sq. km) Water area (2000): 0.022799 sq. miles (0.059050 sq. km) Total area (2000): 48.943396 sq. miles (126.762808 sq. km) Located within: Maryland (MD) Location: 39.658897 N, 77.682970 W