The Snake River, a major river in the Pacific Northeast, originates in Yellowstone National Park, Wyoming, at 9,500 feet. It joins the Columbia River near Pasco, Washington, 1,036 miles from its source. It is the largest tributary of the Columbia River. The River is important in American history and was originally named for Meriwether Lewis  who was the first of the Lewis and Clark Expedition to sight the river in 1805.