It is located at the boundary of the Midwestern and Southern United States, flowing in a southwesterly direction from western Pennsylvania to its mouth on the Mississippi River at the southern tip of Illinois. The Ohio River is a 981-mile (1,579 km) long river in the United States. Little Kanawha River, Kanawha River, Guyandotte River, Big Sandy River, Little Sandy River, Licking River, Kentucky River, Salt River, Green River, Cumberland River, Tennessee Riverīeaver River, Little Muskingum River, Muskingum River, Little Hocking River, Hocking River, Shade River, Scioto River, Little Miami River, Great Miami River, Wabash River