The Jefferson River is a major tributary of the Missouri River located in southwestern Montana. It flows approximately 85 miles, originating from the confluence of the Big Hole River and the Ruby River. The river is known for its scenic beauty and is surrounded by mountains and valleys, making it a popular destination for outdoor activities such as fishing, kayaking, and hiking. The Jefferson River is part of the larger Missouri River Basin and plays a crucial role in the local ecosystem. It supports various wildlife species and provides irrigation for agriculture in the region. The river's historical significance includes its exploration by Lewis and Clark during their expedition in the early 1800s.