 The "American River" part of the Columbia River basin, via the Bumping, Naches, and Yakima rivers.From its source at American Lake, it flows north for several miles, picking up its tributary the Rainier Fork American River, which flows east down from the vicinity of Chinook Pass.State Route 410 crossing Chinook Pass from Mount Rainier National Park, then follows the Rainier Fork and the "American River" valleys.