Pets allowed
Elevation Gain
5,506.00 ft (1,678.23 m)
Trail type
32.20 mi (51.82 km)
Please respect the outdoors by practicing Leave No Trace. Learn more about how to apply the principles of Leave No Trace on your next outdoor adventure here.

The Continental Divide National Scenic Trail spans nearly 3,100 miles across 5 states from Mexico to Canada, traversing a vast array of different environments and landscapes along the way. The CDT can be completed as a single thru-hike that will take 4 to 6 months, or by section-hiking smaller segments. The Montana-Idaho portion of the CDT features nearly 1,000 miles of diverse mountain terrain. You’ll pass alongside the lofty peaks of the Anaconda, Bitterroot and Beaverhead Mountains; walk through the rugged and remote Bob Marshall Wilderness Complex; and finally arrive at the “Crown of the Continent” that is Glacier National Park. In this guide we’ll take a closer look at Montana-Idaho Section 4.

Montana-Idaho Section 4 begins from the Aldous Lake Trailhead where there are picnic tables and a vault toilet nearby. You’ll soon reach the namesake lake, though sadly algae often covers the surface making it less than ideal for a swim.

You’ll continue climbing after the lake, including a few steep ups. Continue along through the relatively unexciting terrain. During summer months this section can get quite hot, making the climbing even less fun.

You’ll pass a few small streams, and a couple tiny ponds. There are slight views from here, but noting spectacular. The trail is also not frequently traveled or well defined in areas.

One last big climb awaits you. After topping out the views become quite nice. Rock Spring is the next water source, a slight trickle out of the mountainside. The trail is easier hiking from this point on. You’ll descend down to a forest road, then have one more steep climb.

The CDT then follows a fence-line as the forest and trees begin to disappear. The trail then connects with a dirt road which it’ll follow for the next 15 miles (it’s only 8 miles however to the end of Section 4).

There is one water source about 4 miles before the end of the section. Then it’s mostly all downhill until you reach Interstate 15. The small town of Lima is commonly accessed from here. This marks the end of Section 4.

Logistics + Planning

Preferable season(s)




Parking Pass


Open Year-round



Some nice mountain views near Rock Spring.


Hot, exposed hiking with some steep climbs for majority of section.

Trailhead Elevation

7,043.00 ft (2,146.71 m)

Highest point

9,164.00 ft (2,793.19 m)


Backcountry camping
Big vistas

Typically multi-day


Permit required



Nearby Lodging + Camping


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