Lewiston Hill, or the Clearwater Escarpment, is the steep rise above the meeting of the Clearwater and Snake rivers at Lewiston, Idaho, and Clarkston, Washington, marking the transition from the low valley cities to the Palouse uplands. Rising about 2,015 feet from the river to the upper edge, it is both a defining natural landmark and a gateway to higher country. The slope is also associated with the Old Spiral Highway, a ten-mile road opened in 1917 that climbed the hill in 64 curves and served as the main northern route for decades before the newer U.S. Route 95 grade replaced it in 1977.