High Quality Content by WIKIPEDIA articles! 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.