West Fork Pahsimeroi

The West Fork Pahsimeroi Road leads deep into the heart of Idaho’s wild Upper Pahsimeroi Valley. Known for its dramatic remoteness and alpine grandeur, this trail winds beneath the towering summits of the Lost River Range, offering views of Idaho’s highest peaks, including Mount Borah and Leatherman Peak.

Accessed via the Upper Pahsimeroi Road, this spur quickly turns primitive, with rough conditions that require a high-clearance vehicle and, in many spots, 4-wheel drive. Expect washouts, exposed rock shelves, and narrow ledges as you climb toward the trailhead.

Despite the moderate challenges, the payoff is immense. The road serves as a gateway to some of the region’s premier hiking and climbing destinations, including the Mahogany Creek drainage and the rugged approaches to Leatherman Peak. At the road’s end, the West Fork Upper Pahsimeroi Trailhead provides access to stunning alpine routes like the Merriam and Pass Lake Trails.

Here, you'll also find primitive campsites complete with picnic tables and established fire rings, ideal for basecamping in a place that feels worlds away. For those seeking high adventure, solitude, and front-row views of Idaho’s tallest mountains, the West Fork Pahsimeroi delivers in full.