Idaho Falls to Butte Road Trip: Gems Along US-20 & I-15

A little-known fact: the stretch of US-20 from Idaho Falls to the Montana border follows the old Oregon Trail route, where emigrants once crossed the Snake River at Eagle Rock—now the site of the Idaho Falls Greenbelt. Today, this 180-mile journey (about 3 hours of driving) offers a mix of sublime volcanic landscapes, dinosaur fossils, and small-town Americana.

This guide answers the key questions: what are the best stops Idaho Falls, ID to Butte, MT; how long to drive Idaho Falls, ID to Butte, MT; is it worth driving Idaho Falls, ID to Butte, MT; and what are things to do between Idaho Falls, ID and Butte, MT. For more on finding hidden gems, check out how to find the best stops and hidden gems between cities.

North of Idaho Falls, US-20 cuts across the Snake River Plain, a flat expanse of ancient lava flows. Near Dubois, you'll enter the Birch Creek Valley, home to the unusual Egin Bench—a volcanic butte with petroglyphs. Further north, the landscape transforms into the rolling grasslands of the Beaverhead Mountains, part of the Continental Divide.

• UNESCO nearby: While no official sites on the route, the Yellowstone National Park (about 2 hours east) is a UNESCO World Heritage Site.
• Local commerce: In Dillon, stop at the Old Hotel Gallery for handcrafted jewelry; in Butte, the Butte Depot hosts a weekend farmers market (summer).

Climate varies dramatically: Idaho Falls averages 20°F in winter to 90°F in summer, with minimal humidity. The pass near Monida can see snow from September to May—check weather before departure. Spring brings wildflowers (lupine, balsamroot) along the roadside, while autumn paints the cottonwoods gold.

The primary route is US-20 west from Idaho Falls to I-15 north at Dubois, then I-15 all the way to Butte. Alternatively, take US-20 directly north through Mud Lake and Monida Pass—slower but more scenic. Fuel is available every 30-40 miles, but plan ahead: between Dubois and Dillon, there's a 70-mile stretch with only one gas station (at the Monida Pass exit).

• Average gas price: $3.50/gal (Idaho) vs $3.70/gal (Montana). Fill up in Idaho Falls.
• Restrooms: Idaho Falls visitors center, Dubois Rest Area (mile 50), Clark Canyon Reservoir (mile 130).
• Wildlife crossings: Watch for deer and antelope between Dubois and Monida Pass, especially at dawn/dusk.

Road quality is excellent: I-15 is paved and well-maintained, while US-20 is two-lane but smooth. Speed limits drop to 35 mph in construction zones near Dillon. For families, the Idaho Falls Zoo at Tautphaus Park is a great start, and the Lemhi County Museum in Salmon (detour east) offers interactive pioneer exhibits.

• Child-friendly pit stops: Dubois' Yellowstone Bear World (drive-thru wildlife park) and Clark Canyon Reservoir picnic area.
• Pet-friendly: Most rest stops allow dogs on leash; Moose Creek Reservoir (mile 160) has a pet-friendly trail.
• Fatigue management: Use the Dubois Rest Area (mile 50) and Dillon Visitor Center (mile 140) for breaks. Avoid driving the Monida Pass after dark.

Hidden off-route spot: Take the Little Sage Creek Road (mile 120) to see the Bannack Ghost Town—Montana's best-preserved gold rush town, only 15 minutes off I-15. No admission fee, and you can tour the old saloon and jail.