North Fork American River
The North Fork American River is the longest branch of the American River in Northern California. It is long from its source at the crest of the Sierra Nevada, near Lake Tahoe, to its mouth at Folsom Lake northeast of Sacramento. Prior to the construction of Folsom Dam the river was about longer making for a total length of .
South Fork Clearwater River
The river is formed by the confluence of the American River and Red River in the Nez Perce National Forest at an elevation of . The roughly American River rises at and flows generally south to the confluence, while the northwest flowing Red River, rising at , is about long. The American River is sometimes considered part of the main stem. From the confluence the South Fork flows west through a canyon followed by Idaho State Highway 14, receiving the Crooked River from the left and Newsome Creek from the right before reaching Golden, where it receives Tenmile Creek from the left. Further west the river receives Johns Creek from the left, Meadow Creek from the right and Mill Creek from the left, and the gorge deepens to a maximum of some as the river swings north near Grangeville. From there the river flows generally north, past Harpster and Stites, before reaching its mouth on the Clearwater at Kooskia, at an elevation of .