SR 906 begins at a half-diamond interchange with I-90, exit 52, in Snoqualmie Pass, King County.

Access to the Pacific Crest Trail is provided from the one of Summit West's parking lots.

Just south of the rest area is an intersection with Yellowstone Road, which links back to I-90 at a full diamond interchange.

Summit Central borders the west side of the highway with parking lots for the ski area on the east side of the highway, as the two-lane 35-mile-per-hour (56 km/h) speed limited road enters the unincorporated community of Hyak and continues southeastward.

[6] Every year, WSDOT conducts a series of surveys on its highways in the state to measure traffic volume.

The Sunset Highway was built as a two-lane road in 1915, and rebuilt along the abandoned right-of-way of the Chicago, Milwaukee, St. Paul and Pacific Railroad in 1926.

[18] WSDOT conducts a series of surveys to measure traffic volume in terms of AADT and calculated that 300 vehicles-per-day used the spur route in 2012.