Fortymile Salmon River Canyon Road — Clayton to Salmon via the Pahsimeroi Valley Back Road
Two mountain ranges, one forgotten valley, zero crowds.
Everyone drives US-93 up the Salmon River Canyon and thinks they’ve seen it. They haven’t seen this. The Pahsimeroi Valley Road branches east at Clayton, cuts north across the broad glacial valley between the Lost River Range and the Lemhi Range, and traces the Pahsimeroi River all the way to its confluence with the Salmon near Ellis. The valley floor is high desert ranching country — hay meadows, irrigation pivots, and BLM benchland backing up against 12,000-foot peaks on both sides. Side tracks push up into the Lost River Range toward Leatherman Peak and the Borah Peak trailhead area. The road is mostly gravel with dirt sections that can washboard badly. It’s not the most technical route Idaho has to offer, but it’s one of the most honest — wide open, genuinely remote, and big enough to make you feel small in the best way.
This is an easy-to-moderate overland route; a high-clearance 2WD handles the main road in dry conditions, but 4WD is preferred when exploring side canyons after rain. No permit required. Dispersed camping is available on BLM sections throughout the valley. Water from the Pahsimeroi River should be filtered. Fuel in Mackay or Salmon — there is nothing in between. Best season is May through October. A shoulder-season bonus: the aspens on the east face of the Lemhis turn gold mid-October and the valley is nearly empty.
Trail Specs
| Difficulty | Easy |
|---|---|
| Trail Type | Overland Route, Scenic Drive |
| Surface | Dirt, Gravel, Mixed |
| Features | Camping, High Altitude, Remote, Scenic |
| Length (miles) | 62 mi / 99.8 km |
| Duration | 1-2 days |
| Max elevation (ft) | 6980 ft |
| Best season | May-October |
| Minimum vehicle | High-clearance 2WD (4WD preferred) |
| Nearest town | Salmon, ID |
| Land manager | BLM Challis Field Office / Salmon-Challis National Forest |
| Permit required | No |
| Cell service | None |
| Water crossings | No |
| Dispersed camping | Yes |
| Official sources | BLM Challis Field Office Salmon-Challis National Forest |
| Start coordinates | |
| End coordinates | |
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Location
Trail Conditions
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Frequently asked questions
Can a stock Tacoma or 4Runner handle this route without modifications?
Yes. High-clearance 2WD can manage this road in dry conditions, but 4WD is preferred for softer sections and any wet weather. A stock Tacoma or 4Runner is more than enough — this is not a technical trail.
When does the road typically open in spring and close in fall?
May through October is the reliable window. Snow can close higher sections early in the season and again by late October — check with BLM Challis Field Office before a spring run, especially before Memorial Day.
Do I need a permit to drive this route or camp along it?
No permit required to drive the route. Dispersed camping on BLM land is free with no reservation needed — standard 14-day stay limit applies. Follow Leave No Trace and check for any fire restrictions, which change seasonally in this part of Idaho.
What's the hardest section and what should I actually expect?
Nothing on this route qualifies as technically difficult — the hardest moments are washboard sections and soft dirt after rain. The canyon narrows near the Salmon River stretch but remains passable. If you're anxious about it, don't be; if you came for a rock crawl, wrong trail.
How far is it between fuel stops, and is there any cell service on the route?
Zero cell service for essentially the entire 62 miles — plan accordingly and download offline maps before you leave. Fuel up in Challis before the Clayton start; Salmon at the north end is your next reliable gas stop, roughly 62 miles of no-service road between them.
Trail track
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