<P> The Snake River is a major river of the greater Pacific Northwest in the United States . At 1,078 miles (1,735 km) long, it is the largest tributary of the Columbia River, the largest North American river that empties into the Pacific Ocean . Rising in western Wyoming, the river flows through the Snake River Plain of southern Idaho, then through the rugged Hells Canyon area via northeastern Oregon and the rolling Palouse Hills, to reach its mouth near the Washington Tri-Cities area, where it enters the Columbia . Its drainage basin encompasses parts of six U.S. states, and its average discharge is over 54,000 cubic feet per second (1,500 m / s). </P> <P> Rugged mountains divided by rolling plains characterize the physiographically diverse watershed of the Snake River . The Snake River Plain was created by a volcanic hotspot which now lies underneath Yellowstone National Park, where the headwaters of the Snake River arise . Gigantic glacial - retreat flooding episodes that occurred during the previous Ice Age carved out many topographical features, including various canyons and ridges along the middle and lower Snake River . Two of these catastrophic flooding events significantly affected the river and its surrounds . </P> <P> More than 11,000 years ago, prehistoric Native Americans lived along the Snake . Salmon from the Pacific Ocean spawned by the millions in the river . These fish were central to the lives of the people along the Snake below Shoshone Falls . By the time Lewis and Clark crossed the Rockies and sighted the valley of a Snake tributary, the Nez Perce and Shoshone were the most powerful peoples in the region . Some tribes adopted use of horses after contact with Europeans, which reshaped their hunting and cultures for the next few hundred years before outside settlement . Later explorers and fur trappers further changed and used the resources of the Snake River basin . At one point, a hand sign made by the Shoshones representing fish was misinterpreted to represent a snake, giving the Snake River its name . </P> <P> By the middle 19th century, the Oregon Trail, a pioneer trail of which a major portion followed the Snake River, had been established by aspiring settlers and traders . Steamboats and railroads moved agricultural products and minerals along the river throughout the 19th and early 20th centuries . The powerful, steep flow of the Snake River has been used since the 1890s to generate hydroelectricity, enhance navigation, and provide irrigation water from fifteen major dams built on the lower river, transforming it into a series of reservoirs . Several of these have been proposed for removal in order to restore some of the river's once - tremendous salmon runs . </P>

How did the snake river get its name
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