Marion -- U.S. County in Indiana Population (2000): 860454 Housing Units (2000): 387183 Land area (2000): 396.248885 sq. miles (1026.279857 sq. km) Water area (2000): 6.789975 sq. miles (17.585955 sq. km) Total area (2000): 403.038860 sq. miles (1043.865812 sq. km) Located within: Indiana (IN), FIPS 18 Location: 39.792792 N, 86.141810 W Headwords: Marion Marion, IN Marion County Marion County, IN