[3] The street travels north over a branch of the Columbia Basin Railroad into Downtown Moses Lake and turns northeast to parallel the Parker Horn before the split between SR 171 and I-90 Business, which becomes Pioneer Way.

[1][4] The highway continues northeast to leave Downtown Moses Lake and end at an intersection with SR 17, which bypasses the city.

[6] Broadway Avenue was originally part of Primary State Highway 18 (PSH 18), which extended from George to Ritzville.

[7][8][9] U.S. Route 10 (US 10) was re-routed onto PSH 18 in the 1940s,[10][11][12] and both highways began using a proposed southern bypass of the city in 1955.

[13] A road connecting Moses Lake to Odessa in the northeast was proposed in the late 1940s,[14] and was signed into law in 1955 as Secondary State Highway 7E.