21010 -- U.S. ZIP code Municipality (1990): GUNPOWDER, Maryland All ZIPs for this municipality (1990): 21010 Population (2000): 864 Housing Units (2000): 255 Land area (2000): 15.935551 sq. miles (41.272885 sq. km) Water area (2000): 0.162022 sq. miles (0.419636 sq. km) Total area (2000): 16.097573 sq. miles (41.692521 sq. km) Located within: Maryland (MD) Location: 39.344808 N, 76.273137 W