River mouth 2,559 feet (780 m) Country United States of America | Length 338 km River system Missouri River | |
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Source Blackfeet Indian Reservation | ||
The Marias River is a tributary of the Missouri River, approximately 210 mi (338 km) long, in the U.S. state of Montana. It is formed in Glacier County, in northwestern Montana, by the confluence of the Cut Bank Creek and the Two Medicine River. It flows east, through Lake Elwell, formed by the Tiber Dam, then southeast, receiving the Teton River at Loma, 2 mi. (3.2 km) above its confluence with the Missouri.
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Map of Marias River, Montana, USA
The river was explored in 1805 by the Lewis and Clark Expedition. Some of the men on the expedition mistook it for the main branch of the Missouri until their subsequent discovery of the Great Falls of the Missouri near Great Falls, Montana. The river was named by Meriwether Lewis after his cousin, Maria Wood.
The river was the scene of the 1870 Marias Massacre.
The Marias is a Class I river from Tiber Dam to its confluence with the Missouri River for public access for recreational purposes.