The three American River forks merge into Folsom Lake Reservoir.

The North Fork is the longest tributary of the American River, at 88 miles (142 km). It begins at an elevation of about 7,900 feet (2,400 m) near Lake Tahoe in Placer County at Mountain Meadow Lake, just northeast of Granite Chief and immediately due west of Palisades/Squaw Valley Ski Resort.

The Middle Fork of the American River is located 30 minutes from Auburn, 50 miles North East of Sacramento, and only 140 miles East of San Francisco.

The South Fork of the American River lies in the golden hillsides of the Sierra Nevada foothills, just forty miles east of Sacramento. The river winds through the tiny hamlet of Coloma (the town where gold was first discovered in California in 1848).