State Route 171 (SR 171, named Broadway Avenue) is a 3.79-mile (6.10 km) long state highway serving the city of Moses Lake in Grant County, located in the U.S. state of Washington. Broadway Avenue begins at an interchange with Interstate 90 (I-90) and travels northeast through Downtown Moses Lake concurrent to Interstate 90 Business and parallel to Parker Horn before ending at an intersection with SR 17. Broadway Avenue was previously part of Primary State Highway 18 (PSH 18) and U.S.