Yellowstone River

The river rises in northwestern Wyoming in the Absaroka Range at the Continental Divide in southwestern Park County. The river starts where the North Fork and the South Fork Yellowstone River converge. The North Fork, the larger of the two forks, flows from Younts Peak. The South Fork flows from the southern slopes of Thorofare Mountain. The Yellowstone River flows northward through Yellowstone National Park, feeding and draining Yellowstone Lake, then dropping over the Upper and Lower Yellowstone Falls at the head of the Grand Canyon of the Yellowstone within the confines of the park. After passing through the Black Canyon of the Yellowstone downstream of the Grand Canyon, the river flows northward into Montana between the northern Absaroka Range and the Gallatin Range in Paradise Valley. The river emerges from the mountains near the town of Livingston, where it turns eastward and northeastward, flowing across the northern Great Plains past the city of Billings.

East of Billings, it is joined by the Bighorn River. Further downriver, it is joined by the Tongue near Miles City, and then by the Powder in eastern Montana. It flows into the Missouri River near Buford, North Dakota just upstream from Lake Sakakawea.

In Montana the river has been used extensively for irrigation since the 1860s. In its upper reaches, within Yellowstone Park and the mountains of Montana, it is a popular destination for fly fishing. The Yellowstone is a Class I river from the Yellowstone National Park boundary to the North Dakota border for the purposes of stream access for recreational purposes.