The Tuscarawas River is a principal tributary of the Muskingum River, 129.9 miles (209 km) long, in northeastern Ohio in the United States. Via the Muskingum and Ohio rivers, it is part of the watershed of the Mississippi River, draining an area of 2,590 square miles (6,700 km2) on glaciated and unglaciated portions of the Allegheny Plateau.

The Muskingum River is a tributary of the Ohio River, approximately 111 miles (179 km) long, in southeastern Ohio in the United States. An important commercial route in the 19th century, it flows generally southward through the eastern hill country of Ohio. Via the Ohio, it is part of the Mississippi River watershed. The river is navigable for much of its length through a series of locks and dams.