Lonesome Highway — Copper Basin Road to Mackay via the Lost River Range Front
Idaho's forgotten volcanic bowl under 12k peaks.
Starting from Mackay on US-93, the Copper Basin Road climbs northeast past the Mackay Reservoir and pushes deep into the Pioneer Mountains, skirting the western flank of the Lost River Range — the same range that holds Mount Borah, Idaho’s highest peak at 12,662 feet. The basin itself is a high-elevation sage flat sitting above 7,000 feet, ringed by jagged ridgelines and cut through by the Big Lost River headwaters. A spur north toward the Salmon River Mountains ties this into a legitimate multi-day loop. The road passes old mining claims and historic sheep camps, and you’ll likely see pronghorn and mule deer before you see another vehicle.
The main Copper Basin loop is a solid high-clearance run — stock 4WD handles it fine in dry conditions, but snow lingers into June and returns by October, and some creek crossings after spring runoff require careful line selection. No permit needed, dispersed camping throughout, and the BLM Challis Field Office manages the area. Fuel up in Mackay before you leave — there’s nothing in the basin. Cell service drops to zero past the reservoir. This is the kind of Idaho backcountry that makes you wonder why everyone crowds the Sawtooths.
Trail Specs
| Difficulty | Moderate |
|---|---|
| Trail Type | Backcountry, High Clearance, Overland Route |
| Surface | Dirt, Gravel |
| Features | Camping, High Altitude, Remote, Scenic, Water Crossings |
| Length (miles) | 48 mi / 77.2 km |
| Duration | 1-2 days |
| Max elevation (ft) | 7800 ft |
| Best season | July-September |
| Minimum vehicle | Stock 4WD high-clearance |
| Nearest town | Mackay, ID |
| Land manager | BLM Challis Field Office |
| Permit required | No |
| Cell service | None |
| Water crossings | Yes |
| Dispersed camping | Yes |
| Official sources | blm.gov |
| Start coordinates | |
| End coordinates | |
| Copy both for Google Maps directionsClick to copy the directions URL · or open it directly in a new tab | |
| Find on Google | Search on Google → |
Location
Trail Conditions
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Frequently asked questions
Can a stock 4Runner or Tacoma handle this route without modifications?
Yes, a stock high-clearance 4WD like a 4Runner or Tacoma is the minimum you want here. The surface is dirt and gravel with no extreme rock sections, but ruts, loose crossings, and 48 miles of washboard will punish low-clearance rigs and street tires.
When does the Copper Basin Road actually open and close for the season?
July through September is the reliable window. Snow can close higher sections well into June and return early in October — Copper Basin sits above 7,000 feet and the Lost River Range holds cold. Don't gamble the shoulder months without checking with the BLM Challis Field Office directly.
Do I need a permit to run this route or camp out there?
No permit required. This is BLM land managed by the Challis Field Office, and dispersed camping is allowed under standard BLM rules — 14-day stay limit, pack out everything, camp 200 feet from water sources.
What's the hardest section and what should I actually expect?
The water crossings are where unprepared rigs get caught — depths vary by season and early July crossings run higher from snowmelt. The route itself is moderate, but remoteness amplifies any mechanical problem; 48 miles with zero cell service means a busted CV axle is your problem to solve alone.
How far is the nearest gas from the start and end of the route?
Mackay at the northern end has a gas station — fill up there before heading south into Copper Basin. The southern trailhead near Copper Basin Road is roughly 30+ miles from any fuel, so top off in Mackay or Arco before you commit to the loop.
Trail track
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