The highway heads northward, and ascends the Big Wood River valley, into Blaine County, past the Magic Reservoir to the west and crosses US-20 at Timmerman Junction at 4,884 feet (1,490 m).

It runs northward down the valley with the Salmon River to Obsidian and Stanley, with the Sawtooths to the immediate west and the White Cloud Mountains to the slightly more distant east.

In 1824, while searching the mountain wilderness of present-day Idaho, known then as Columbia District, for beaver, Alexander Ross came up the Wood River and discovered Galena Summit on September 18.

Leading a large brigade of Hudson's Bay Company trappers, he wondered if he could get through unknown mountains and rocky defiles that obstructed his passage back to his base of operations at present Challis.

[1] In 2020, the Idaho Transportation Department (ITD) proposed abandoning the spur route, transferring ownership at the request of Blaine County due to urban growth along the corridor.