Marion -- U.S. County in Mississippi Population (2000): 25595 Housing Units (2000): 10395 Land area (2000): 542.342770 sq. miles (1404.661267 sq. km) Water area (2000): 6.236379 sq. miles (16.152148 sq. km) Total area (2000): 548.579149 sq. miles (1420.813415 sq. km) Located within: Mississippi (MS), FIPS 28 Location: 31.240902 N, 89.823725 W Headwords: Marion Marion, MS Marion County Marion County, MS