Washington State Route 181

State Route 181
Valley Highway
SR 181 is highlighted in red.
Route information
Maintained by WSDOT
Length	6.05 mi[1] (9.74 km)
Existed	1964[2]–present
Major junctions
South end	SR 516 in Kent
North end	I-405 in Tukwila
Location
Country	United States
State	Washington
County	King
Highway system
State highways in Washington Interstate US State Scenic Pre-1964 1964 renumbering Former
← SR 174 → I-182

State Route 181 (SR 181, named the Valley Highway) is a 6.05-mile-long (9.74 km) state highway serving King County in the U.S. state of Washington. The highway, travelling north parallel to the Green River, begins at SR 516 in Kent and ends at an interchange with Interstate 405 (I-405) in Tukwila. The highway primarily serves as an alternate route to the SR 167 freeway, which travels east parallel to SR 181.

The original route, between Auburn and Rainier Valley in Seattle, was originally established in 1931 as a branch of Primary State Highway 1 (PSH 1) and in 1937 as Secondary State Highway 5M (SSH 5M). SSH 5M was renumbered to SSH 2M in 1959 and became SR 181 after the 1964 highway renumbering. SR 181 was shortened twice in the 1970s from Seattle to Tukwila and once more in 1991 from Auburn to Kent to form its present route, no longer connected to parent route SR 18.