State Route 129 (SR 129) is a state highway in Asotin County, Washington, United States. It travels north–south at the southeastern corner of the state, connecting with Oregon Route 3 (OR 3) at the Oregon state line south of Anatone. The 43-mile (69 km) highway then follows the Snake River, which marks the Idaho state border, north to Clarkston and terminates at U.S. Route 12 (US 12). SR 129 also has a short spur route that connects to a separate intersection with US 12 in Clarkston.