Lonesome Highway — Centennial Range Road to Macks Inn via Targhee Creek Divide
The divide nobody talks about.
The Centennial Mountains form the Continental Divide’s westernmost sweep before it turns north into Montana proper, and the range is so remote that most people drive right past it on US-20 without knowing it exists. Centennial Range Road — a series of connected USFS two-tracks — climbs north from Macks Inn, Idaho, toward the Montana state line and runs the crest near Targhee Creek Pass at around 8,700 feet. The views from the divide take in the Island Park caldera to the south, a volcanic depression the size of Rhode Island, and the Centennial Valley’s wetlands to the north. The route ties into Red Rock Pass Road on the Montana side. The high section is genuinely rough: loose rock, wet meadow crossings, and the occasional blowdown.
This is a Difficult route — the crest section requires a capable short-wheelbase 4WD, recovery gear, and patience. Clearance matters here; the two-tracks are narrow and the crown is high. Best season is July through September; snow can close the crest well into June and returns in October. No permit required. Fuel in Macks Inn; the nearest real services are in Ashton, Idaho. Cell service is nonexistent on the divide. Dispersed camping is excellent on both sides of the state line. This is one of those routes where you might go an entire day without seeing another vehicle — which is exactly the point.
Trail Specs
| Difficulty | Difficult |
|---|---|
| Trail Type | Backcountry, High Clearance, Overland Route |
| Surface | Dirt, Gravel, Mixed |
| Features | Camping, High Altitude, Remote, Scenic |
| Length (miles) | 34 mi / 54.7 km |
| Duration | 1-2 days |
| Max elevation (ft) | 8700 ft |
| Best season | July-September |
| Minimum vehicle | Short-wheelbase high-clearance 4WD |
| Nearest town | Macks Inn, ID |
| Land manager | USDA Forest Service — Caribou-Targhee National Forest |
| Permit required | No |
| Cell service | None |
| Water crossings | Yes |
| Dispersed camping | Yes |
| Official sources | Caribou-Targhee NF Recreation |
| Start coordinates | |
| End coordinates | |
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Location
Trail Conditions
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Frequently asked questions
Can a long-wheelbase truck like a full-size F-250 run this trail?
It's not recommended. The trail is rated for short-wheelbase high-clearance 4WD — tight switchbacks and off-camber sections on the Targhee Creek divide will punish long overhangs. A short-wheelbase rig with lockers handles it much better.
When does this route typically open and close each year?
July through September is the reliable window. The Centennial Range holds snow well into June, and early October storms can close the divide fast. Check with Caribou-Targhee NF before heading out — conditions vary year to year.
Do you need a permit to run this route or camp along it?
No permit required as of now. The route runs through Caribou-Targhee National Forest, dispersed camping is allowed, and there are no fees to drive or camp here. Standard Leave No Trace rules apply.
What's the hardest section and what should I actually expect?
The crest near the Targhee Creek Divide is where it gets serious — loose rocky two-track, steep grades, and off-camber shelf road with limited recovery space. Plan for slow going, have a spotter ready, and don't attempt it solo without a recovery kit.
Are there reliable water sources on the trail, and how far is the nearest gas?
There are water crossings along the route but treat everything — bring a filter. For gas, Macks Inn is your closest option at the north end; fuel up before you start because you'll have zero cell service for the entire 34 miles and no bailout options mid-route.
Trail track
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