Fairfield -- U.S. County in Ohio Population (2000): 122759 Housing Units (2000): 47922 Land area (2000): 505.110654 sq. miles (1308.230532 sq. km) Water area (2000): 3.486127 sq. miles (9.029027 sq. km) Total area (2000): 508.596781 sq. miles (1317.259559 sq. km) Located within: Ohio (OH), FIPS 39 Location: 39.776158 N, 82.636683 W Headwords: Fairfield Fairfield, OH Fairfield County Fairfield County, OH