21659 -- U.S. ZIP code Municipality (1990): RHODESDALE, Maryland All ZIPs for this municipality (1990): 21659 Population (2000): 1530 Housing Units (2000): 701 Land area (2000): 51.876800 sq. miles (134.360290 sq. km) Water area (2000): 0.124959 sq. miles (0.323642 sq. km) Total area (2000): 52.001759 sq. miles (134.683932 sq. km) Located within: Maryland (MD) Location: 38.575260 N, 75.781770 W