20778 -- U.S. ZIP code Municipality (1990): WEST RIVER, Maryland All ZIPs for this municipality (1990): 20778 Population (2000): 1796 Housing Units (2000): 673 Land area (2000): 8.743505 sq. miles (22.645572 sq. km) Water area (2000): 0.000000 sq. miles (0.000000 sq. km) Total area (2000): 8.743505 sq. miles (22.645572 sq. km) Located within: Maryland (MD) Location: 38.832265 N, 76.556040 W