Red Rock Pass is a low mountain pass in southern Bannock County Idaho, United States, south of Downey. It is geologically significant as the spillway of ancient Lake Bonneville. It is located along highway U.S. Route 91 at an elevation of 4,785 feet (1,458 metres) above sea level, bounded by two mountain ranges; the to the east and the to the west. The pass was cut through resistant Paleozoic shale, limestone, and dolomite, and forms a narrow gap two miles (3.2 km) in length.At one time the pass was 300 feet (91 metres) higher, where the shoreline of Pleistocene Lake Bonneville stood.