Salmon to Thermopolis: Road Trip Guide with Hidden Gems

Starting in Salmon, Idaho, the route to Thermopolis, Wyoming, follows U.S. 93 south to I-15, then east on U.S. 20/26 through Idaho Falls and into Wyoming, eventually joining U.S. 20/14/16 through Dubois and down to Thermopolis. The drive covers roughly 330 miles and typically takes 6 to 6.5 hours of pure driving time, but you'll want to add at least a day for stops.

This corridor traces the path of the ancient Idaho-Wyoming border, where the Snake River Plain meets the Rocky Mountains. You'll cross the Continental Divide at Togwotee Pass (elevation 9,658 feet) on U.S. 26/287, a gateway to the Wind River Range. The geology is a story of volcanic eruptions and glacial carving—visible in the lava fields near Arco and the red cliffs at Thermopolis.

Before you set out, check the weather: the pass can have snow from October through May. The route offers a mix of high desert, mountain forests, and river canyons, with vistas that change dramatically every hour.

This guide covers the essentials: how long to drive Salmon, ID to Thermopolis, WY, best stops, safety, and family considerations. For more on hidden gems between cities, see how to find the best stops and hidden gems between cities.

Climatic conditions vary dramatically: summer temperatures can exceed 90°F in the valleys, while winter brings heavy snow and icy roads, especially over Togwotee Pass. Always carry winter chains in cold months and extra water in summer.

For family suitability, consider a stop at the Idaho Falls River Walk—a paved path along the falls with playgrounds—or the Heise Hot Springs near Ririe, which has a pool and waterslide. In Thermopolis, the Hot Springs State Park offers a free state bathhouse, a hit with kids.

Fatigue management is crucial: the long, straight stretches can lull you into drowsiness. Plan to stop every two hours at one of the many rest areas, such as the one at Spencer (elevation 5,900 ft) or the Wind River Visitor Center near Dubois. Both have picnic tables and restrooms.

Infrastructure safety is good, with cell service available in most towns but not continuous on the passes. Download offline maps before you go.

For a unique cultural stop, visit the National Historic Trails Interpretive Center in Casper, though it's a slight detour; along the route, the small museum in Dubois is worth 30 minutes.

The natural landscapes on this route are nothing short of spectacular. Just south of Salmon, you'll pass through the Lemhi Valley, where the Lemhi River offers a chance to spot elk and moose. Near Arco, the surreal Craters of the Moon National Monument & Preserve showcases volcanic craters and lava tubes—a must-see for geology enthusiasts. Further east, the Wind River Canyon south of Thermopolis is a deep limestone gorge with towering walls and excellent rafting.

Your route passes within a short detour of two UNESCO World Heritage Sites: Yellowstone National Park (via West Yellowstone) and Grand Teton National Park (via Jackson). Although not directly on the main route, a side trip to these parks adds 2-3 days but is unforgettable.

Local commerce thrives in small towns like Ashton, known for its potato farms, and Dubois, a gateway to the Wind River Indian Reservation. You'll find roadside stands selling fresh produce and handmade crafts, particularly in late summer.

Hidden off-route spots include the Dry Creek Petrified Forest near Dubois, where you can see ancient trees turned to stone, and the Rainbow Curve viewpoint above Thermopolis. These require a short hike but reward with solitude.

Fuel economy is a primary concern on this route, as distances between services can be significant. Plan to fill up in Salmon, Idaho Falls, and Dubois—the latter is the last major town before Thermopolis. Regular unleaded prices along the route average about 10-15% higher than the national average, with remote stations like in Spencer charging a premium.

Road quality is generally good: U.S. 93 and I-15 are well-maintained interstates, while U.S. 26/287 are two-lane highways with decent asphalt. However, sections near Togwotee Pass have frost heaves and potholes in spring, so drive cautiously.

Culinary infrastructure along the route is sparse but adequate. Salmon has a few family diners, Idaho Falls offers a broad choice from fast food to sit-down restaurants, and Dubois has a couple of classic cowboy cafes. Beyond that, expect gas station snacks and picnic spots.

For pets, most rest areas have designated pet-walk areas, but leash laws apply. In Thermopolis, Hot Springs State Park allows leashed pets in most outdoor areas, but not in the bathhouses.