Portsmouth, OH -- U.S. city in Ohio Population (2000): 20909 Housing Units (2000): 10248 Land area (2000): 10.769958 sq. miles (27.894062 sq. km) Water area (2000): 0.287746 sq. miles (0.745259 sq. km) Total area (2000): 11.057704 sq. miles (28.639321 sq. km) FIPS code: 64304 Located within: Ohio (OH), FIPS 39 Location: 38.743186 N, 82.965436 W ZIP Codes (1990): 45663 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Portsmouth, OH Portsmouth