State Route 174 (SR 174) is a 40.66-mile (65.44 km) long state highway that traverses Douglas, Grant and Lincoln counties in Washington. SR 174 begins at a junction with SR 17 in Leahy and travels eastward to Grand Coulee, near the Grand Coulee Dam, to intersect SR 155. From Grand Coulee, the roadway travels southeast to end at SR 21 northwest of Wilbur.

State Route 17 (SR 17) is a 136.67-mile-long (219.95 km) state highway serving the Columbia Plateau in the central region of the U.S. state of Washington. The highway travels through mostly rural areas of Franklin. Adams, Grant, Douglas, and Okanogan counties and is designated as part of the National Highway System between Mesa and Moses Lake and as the Coulee Corridor Scenic Byway between Othello and Coulee City for passing through the Grand Coulee. SR 17 begins in Mesa at an interchange with U.S. Route 395 (US 395) and travels north and intersects SR 26 near Othello before entering Moses Lake, where the highway intersects Interstate 90 (I-90) and travels as a partial expressway. SR 17 continues north, intersecting SR 28 in Soap Lake, through the Grand Coulee to a short concurrency with US 2 west of Coulee City. The highway turns northwest and crosses the Columbia River on the Columbia River Bridge at Bridgeport before ending at US 97 in Brewster at the southwestern edge of the Colville Indian Reservation.