As defined in state law from 1923 to 1937, the Cascade Wagon Road began at a junction with the Methow Valley Highway in Twisp and headed westerly upstream along the Twisp River to Twisp Pass, then downstream along Bridge Creek to the vicinity of its mouth at the Stehekin River. The road then headed uphill again, this time westerly along the Stehekin River to Cascade Pass. Following the Cascade River downstream from the pass, the Cascade Wagon Road crossed the Skagit River near the mouth of the Cascade and ended at Marblemount.
Although the state did some construction along this route, much of the route had not been built by 1937. The road from Twisp most of the way to Twisp Pass was opened to traffic but the highway over the top of the pass and down along Bridge Creek was not. Part of the road along the lower elevation of the Stehekin was built but the last section up to Cascade Pass was not. Most of the road downhill from Cascade Pass to Marblemount, including the bridge across the Skagit, was built in the 1930s.
In 1937, the Cascade Wagon Road was redesignated as Primary State Highway 17.
The Stehekin Branch of the Cascade Wagon Road began at its junction with the trunk of the Cascade Wagon Road near the confluence of Bridge Creek with the Stehekin River. This branch headed downstream along the river and ended at the community of Stehekin on Lake Chelan at the mouth of the river. The Stehekin Branch of the Cascade Wagon Road became a branch of Primary State Highway 17 in 1937.
Primary State Hwys Secondary State Hwys
State Roads 1923-37