21133 -- U.S. ZIP code Municipality (1990): RANDALLSTOWN, Maryland All ZIPs for this municipality (1990): 21133 Population (2000): 28526 Housing Units (2000): 11020 Land area (2000): 9.914236 sq. miles (25.677751 sq. km) Water area (2000): 0.000000 sq. miles (0.000000 sq. km) Total area (2000): 9.914236 sq. miles (25.677751 sq. km) Located within: Maryland (MD) Location: 39.376372 N, 76.799160 W