Washington State Route 172

State Route 172
SR 172 is highlighted in red.
Route information
Auxiliary route of SR 17
Maintained by WSDOT
Length	35.01 mi[1] (56.34 km)
Existed	1964[2]–present
Major junctions
West end	US 2 near Waterville
East end	SR 17 near Leahy
Location
Country	United States
State	Washington
Counties	Douglas
Highway system
State highways in Washington Interstate US State Scenic Pre-1964 1964 renumbering Former
← SR 171 → SR 173

State Route 172 (SR 172) is a 35.01-mile (56.34 km) long state highway serving rural Douglas County in the U.S. state of Washington. The highway travels north from U.S. Route 2 (US 2) near Waterville through Withrow and east through Mansfield before ending at SR 17 at Sims Corner. The highway follows the route of a county road built in the 1930s and signed as Secondary State Highway 10B (SSH 10B) in 1955. SSH 10B became SR 172 during the 1964 highway renumbering and served a daily average of less than 700 vehicles in 2011.