21779 -- U.S. ZIP code Municipality (1990): ROHRERSVILLE, Maryland All ZIPs for this municipality (1990): 21779 Population (2000): 718 Housing Units (2000): 268 Land area (2000): 7.335304 sq. miles (18.998349 sq. km) Water area (2000): 0.000000 sq. miles (0.000000 sq. km) Total area (2000): 7.335304 sq. miles (18.998349 sq. km) Located within: Maryland (MD) Location: 39.431058 N, 77.661691 W