Lonesome Highway — Centennial Mountains Divide Road to Henry’s Lake via Targhee Creek Bench
Ride the spine where Idaho meets Montana.
The Centennial Mountains form one of the few east-west-running ranges in the Rockies, and the ridge road that traces their spine above Henry’s Lake is as remote as it gets in this corner of Idaho. You leave US-20 near Targhee Creek and climb fast onto a bench that puts you above 8,000 feet within a few miles, threading through lodgepole and subalpine meadows with the Henry’s Lake basin spread below and the Continental Divide marking your northern fence. The road runs BLM and USFS doubletrack west along the range crest before dropping back toward the flats near Macks Inn — wildlife is thick here, including moose in the willow draws and pronghorn on the open benches.
This is a high-clearance route that rewards stock 4WD rigs with decent ground clearance and all-terrain tires; no technical rock crawling, but soft shoulders, muddy cuts after rain, and snow drifts that persist into July make timing everything. Best window is mid-July through September. No permits. Fuel in West Yellowstone or Island Park — top off before you leave pavement. Cell service is essentially zero along the crest. Dispersed camping is available on BLM land along the bench.
Trail Specs
| Difficulty | Moderate |
|---|---|
| Trail Type | Backcountry, High Clearance, Overland Route |
| Surface | Dirt, Gravel, Mixed |
| Features | Camping, High Altitude, Remote, Scenic, Wildlife |
| Length (miles) | 28 mi / 45.1 km |
| Duration | 1-2 days |
| Max elevation (ft) | 8640 ft |
| Best season | July-September |
| Minimum vehicle | Stock 4WD high-clearance |
| Nearest town | Macks Inn, ID |
| Land manager | Caribou-Targhee National Forest / BLM Idaho Falls Field Office |
| Permit required | No |
| Cell service | None |
| Water crossings | Yes |
| Dispersed camping | Yes |
| Official sources | Caribou-Targhee NF recreation page BLM Idaho Falls District Office |
| Start coordinates | |
| End coordinates | |
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Location
Trail Conditions
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Frequently asked questions
Can a stock 4Runner or Tacoma handle this trail without modifications?
Yes — a stock 4WD high-clearance vehicle is the minimum and handles this trail fine under normal summer conditions. Soft soil after rain can get slick on the steeper ridge sections, so all-terrain tires are a real advantage over stock A/S rubber.
When does the Centennial Divide Road actually open each year?
July through September is the reliable window — snowpack at 8,600 ft can keep the upper sections closed or dangerously soft well into June. Check current road conditions with Caribou-Targhee NF before you go; early July openings vary year to year.
Do you need a permit or pay any fees to drive this route?
No permit is required and there's no fee to drive the route itself. Dispersed camping on Caribou-Targhee National Forest land is free; follow Leave No Trace rules and the 14-day stay limit.
What's the hardest section and what should I actually expect?
The Targhee Creek Bench stretch has the loosest surface and steepest off-camber pitches — nothing technically extreme, but it'll pucker you if the ground is wet. The bigger issue is exposure: the ridge is narrow in spots with limited room to turn around if you meet oncoming traffic.
Are there any water crossings on this route and can I find water for camp?
There are water crossings near the Targhee Creek drainage — typically shallow in summer but depth varies with snowmelt. Cell service is nonexistent the entire route, so carry enough water for the full trip and treat anything you pull from the creek.
Trail track
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