20637 -- U.S. ZIP code Municipality (1990): HUGHESVILLE, Maryland All ZIPs for this municipality (1990): 20637 Population (2000): 4418 Housing Units (2000): 1435 Land area (2000): 30.117001 sq. miles (78.002672 sq. km) Water area (2000): 0.092128 sq. miles (0.238611 sq. km) Total area (2000): 30.209129 sq. miles (78.241283 sq. km) Located within: Maryland (MD) Location: 38.523408 N, 76.754358 W