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.
Noted frontier explorer, Christopher Gist, reached the Big Sandy Creek tributary of the river on December 4, 1751. Traveling down the river, he arrived at the large Wyandot town of Muskingum, at present Coshocton, on December 14, where he remained for the following month.
Marietta was founded in 1788 as the first permanent settlement in the Northwest Territory, on the mouth of the Muskingum River along the Ohio River. The Big Bottom Massacre occurred along its banks in 1791. Zanesville was settled in 1799 at the site where Zane's Trace crossed the Muskingum at the mouth of the Licking River. In the mid-19th century the Muskingum was an important commercial shipping route, with dams and locks controlling the water level to allow boats to travel up and down the river. With the decrease in use of water-based transportation in Ohio in the 1920s, the locks fell into disrepair. Since the 1960s the locks have been repaired to enable pleasure craft to travel the entire navigable length of the river. The Muskingum waterway is one of the few remaining systems to use hand-operated river locks in the U.S. The navigation system has been designated a Historic Civil Engineering Landmark. In 2006, it was designated "An Ohio Water Trail;" this designation provides for increased canoe access on the river.
In the 1970s, boaters were occasionally allowed to operate the old-fashioned lock mechanisms themselves, with the permission of the lockmaster. The procedure appears to have become more formalized since then.
From around 1812 to 1861 the Muskingum River, located north of the Mason-Dixon Line, was a major Underground Railroad route used by fugitive slaves escaping from the South on their journey north to Lake Erie and Canada.