State Route 8 (SR 8) is a state highway in Grays Harbor and Thurston counties, of the U.S. state of Washington. It extends from U.S. Route 12 (US 12) in the city of Elma, east to an interchange with US 101 about northwest of the state capital, Olympia. SR 8 intersects SR 108 west of McCleary. The route connects Elma and Olympia as part of a corridor between Aberdeen and the Puget Sound region.