The South Fork Musselshell River is a

tributary A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drai ...

of the

Musselshell River The Musselshell River is a tributary of the Missouri River, long from its origins at the confluence of its North and South Forks near Martinsdale, Montana to its mouth on the Missouri River. It is located east of the Continental divide entir ...

in south central

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...

in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

. It rises in the

Lewis and Clark National Forest Lewis and Clark National Forest is located in west central Montana, United States. Spanning , the forest is managed as two separate zones. The eastern sections, under the Jefferson Division, is a mixture of grass and shrublands dotted with "islan ...

in the

Crazy Mountains The Crazy Mountains, often called the Crazies, is a mountain range in the Central Montana Alkalic Province in the U.S. state of Montana. They are a part of the northern Rocky Mountains. Geography Spanning a distance of 40 miles (64 km) ...

in southern Meagher County. It flows northeast, joining the North Fork to form the Musselshell near Martinsdale just west of county line with Wheatland County.

See also