Idaho Falls to Yellowstone: Distance, Route, and What to Do

Idaho Falls to Yellowstone: Distance, Route, and What to Do

Idaho Falls sits 110 miles west of West Yellowstone via US-20 East — about 1.75 hours of driving through some of the most underrated scenery in Idaho. Most travelers treat this as a transit corridor. They're missing significant stops along the way.

The Route: US-20 East from Idaho Falls

Leave Idaho Falls on US-20 East toward Rexburg. The first 40 miles pass through the upper Snake River Plain — flat, agricultural, and honest. After Rexburg, the highway begins a gradual climb into the Targhee National Forest foothills.

The terrain transitions dramatically around mile 50. Lodgepole pines replace farmland, the altitude rises toward 6,500 feet, and the road enters the Island Park caldera — a massive ancient volcanic depression 18 miles wide, filled with dense forest and bisected by the Henry's Fork river drainage.

What to Do Along the Route

Rexburg, Idaho (25 miles / 30 min from Idaho Falls) Small college town. Notable for: good breakfast and coffee options, the Rexburg Idaho Temple for architecture photography, and nearby recreational areas around Ririe Reservoir. Useful 15–20 minute stop.

Island Park, Idaho (85 miles / 1.25 hours from Idaho Falls) Island Park is simultaneously a geographic caldera, a community name, and a 33-mile stretch of US-20 that claims the title of the longest main street in America. This is where the outdoor activity density begins.

Mesa Falls Scenic Byway (turn south at Ashton, Idaho) A detour adds 30–45 minutes but delivers two of Idaho's most impressive waterfalls — Upper and Lower Mesa Falls on the Henry's Fork of the Snake River. Upper Mesa Falls drops 114 feet through an unaltered basalt canyon, one of the last undisturbed waterfalls on the Columbia River system. Genuinely worth the time.

Harriman State Park (90 miles from Idaho Falls) Former Union Pacific Railroad ranch converted to a state wildlife refuge. The Railroad Ranch unit harbors trumpeter swans, sandhill cranes, river otters, and moose in wetland habitat along the Henry's Fork. Easy walking trails from the parking area.

ATV Expedition from Island Park Before reaching West Yellowstone, consider timing your day around a Nomad Yellowstone expedition from Island Park. The operation sits directly on US-20, making it a natural mid-journey activity rather than a backtrack. Morning, mid-day, and evening departures available.

Arriving in West Yellowstone

From Island Park, US-20 continues east 20 miles to West Yellowstone, crossing the Montana border approximately 5 miles before town. The West Entrance to Yellowstone is right on the eastern edge of town.

Idaho Falls as a Yellowstone Base

Idaho Falls is a legitimate base camp option that most travelers overlook. It has a commercial airport (Idaho Falls Regional, served by Delta and United), a full range of hotel and dining options, and sits 1.75 hours from the park — comparable to Bozeman's 1.5-hour drive.

Advantages of Idaho Falls as base: lower accommodation prices, access to the western Idaho landscape, and proximity to Island Park which puts the ATV expedition accessible as a full activity rather than a long day trip.

The US-20 corridor becomes deeply familiar over a 3–5 day Yellowstone trip based from Idaho Falls — and it's a road worth knowing well.

Practical Notes

• Gas in Island Park and West Yellowstone costs 20–40 cents per gallon more than Idaho Falls. Fill up before leaving.
• US-20 east of Rexburg has minimal services for 60+ miles. Have water and snacks in the car.
• The drive through Targhee National Forest (miles 50–80) can experience afternoon thunderstorms in summer — watch for dark buildup over the mountains to the east.

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