Coeur d'Alene to Thermopolis Road Trip Guide: Scenic Drive Through Idaho and Wyoming

The 530-mile journey from Coeur d'Alene, Idaho to Thermopolis, Wyoming traces the edge of an ancient inland sea. This drive, primarily along I-90 east to I-94 and then US-20, passes through landscapes once submerged under the Cretaceous Western Interior Seaway. The highway segments include 8 hours of driving time (excluding stops), crossing the Bitterroot Range and the high plains of Montana before descending into the Big Horn Basin.

A surprising fact: near Butte, Montana, you'll cross the Continental Divide at an elevation of 6,390 feet via the Homestake Pass. The route also passes within 20 miles of the historic site where Sacagawea's family lived. For those wondering is it worth driving Coeur d'Alene, ID to Thermopolis, WY, the answer is a resounding yes—especially for geology buffs and hot spring enthusiasts.

The best stops Coeur d'Alene, ID to Thermopolis, WY include natural wonders like Yellowstone's northern edge and human-made marvels like the Grant-Kohrs Ranch. Use this how to find the best stops and hidden gems between cities guide to uncover lesser-known spots. Below is a quick overview of distances and estimated times.

Natural Landscapes & Attractions: This drive offers diverse geology. From the glacial lakes of Idaho to the smoke-jumper history of Missoula, and the copper mines of Butte (the "Richest Hill on Earth"), each region has a distinct character. In Wyoming, the Big Horn Basin unfolds with rust-colored cliffs and the Wind River Canyon, a stunning 20-mile gorge carved by the Wind River.

• Coeur d'Alene to Lookout Pass (ID/MT border): dense forest, scenic overlooks.
• Butte, MT: Berkeley Pit, a former open-pit copper mine (now a superfund site, but an eerie sight).
• Wind River Canyon, WY: 2,500-foot cliffs, ancient rock layers visible; a must-stop for photographers.

UNESCO World Heritage Sites: While there are no UNESCO sites directly on this route, a slight detour to Yellowstone National Park (about 2 hours south of Thermopolis) is worth considering. The park, a UNESCO World Heritage site, features the famous Old Faithful geyser. Also nearby is the World Heritage-listed Waterton-Glacier International Peace Park (a big detour north from Missoula).

Culinary Infrastructure: Local cuisine reflects the region's ranching and mining heritage. Try huckleberry treats in Idaho, pasties (a Cornish miner's pie) in Butte, and bison burgers in Wyoming. In Thermopolis, the Star Plunge Restaurant serves classic American fare. For quick bites, truck stops offer surprisingly good burritos and coffee.

Local Commerce & Culture: Butte's historic uptown district has antique shops and the Mining Museum. Thermopolis is famous for its free hot springs at the State Bath House. Along US-20, small towns like Shoshoni and Thermopolis host rodeos and Pow Wows in summer. The Wind River Indian Reservation (home to the Eastern Shoshone and Northern Arapaho) borders Thermopolis; explore the Wind River Heritage Center for cultural insights.

Hidden Off-Route Spots: Just off I-90 in Montana, stop at the town of Philipsburg (exit 201) for its historic saloon and sapphire mining. Near Thermopolis, the Legend Rock Petroglyph Site (20 miles north) features over 300 ancient rock carvings. Also, the Ghost Town of Kirwin (dirt road, 4WD recommended) is an abandoned mining settlement in the Absaroka Mountains.

This route is well-traveled and maintained, with ample services. Key highways: I-90 from Coeur d'Alene to Butte, then I-94 and US-20 to Thermopolis. The entire drive is paved, and cell coverage is generally good except in mountain passes and rural Wyoming stretches.

Fuel and Route Economics: Gas prices vary; filling up in Idaho (often 10-20 cents cheaper per gallon than Montana/Wyoming) is advisable. Average fuel cost for a sedan: ~$60-80. Plan fuel stops in Coeur d'Alene, Missoula, Butte, and Greybull, WY.

• Missoula, MT (mile 190): multiple stations, including Costco.
• Butte, MT (mile 310): cheap gas near the I-90/I-15 interchange.
• Greybull, WY (mile 480): last stop before Thermopolis; prices slightly higher.

Climatic Conditions & Route Aesthetics: Summer (June-August) brings clear skies and temperatures 70-90°F, but afternoon thunderstorms are common in Montana. Winter (Nov-Mar) can be severe with snow and ice on Homestake Pass and US-20. Spring and fall offer mild weather and fewer tourists. The aesthetic shifts from pine forests in Idaho to wide Montana valleys and finally to Wyoming's badlands.

Infrastructure Safety & Road Quality: Roads are excellent; I-90 is a divided highway with shoulders. US-20 from Greybull to Thermopolis is a two-lane road with moderate curves; watch for wildlife at dawn/dusk. Emergency services exist roughly every 50 miles. The route passes near the site of a 1959 earthquake that formed Quake Lake, a sobering reminder of nature's power.

Family and Child Suitability: This road trip is family-friendly with many kid-oriented attractions. Butte's Our Lady of the Rockies overlook offers a giant statue and views. In Thermopolis, the Wyoming Dinosaur Center has life-sized skeletons and a working dig site. Hot Springs State Park has a free public pool (with a water slide) that kids love.

• Missoula's Carousel for ages 2-12: hand-carved horses, a miniature steam train.
• Greybull's Museum of Flight and Aerial Firefighting (aerial firefighting history).
• Thermopolis: Hellie's Pond fishing area (free, catch-and-release).

Pet-Friendly Framework: Most national forest lands and state parks welcome leashed pets. Hotels along the route, like La Quinta in Butte and Best Western in Thermopolis, allow pets for a fee. Rest stops in Montana have designated pet areas. Be aware of wildlife; keep dogs on leash near Yellowstone exits.

Fatigue Management & Rest Zones: The drive exceeds 8 hours; plan to stop every 2 hours. I-90 has rest areas near St. Regis (mile 162) and an official Montana rest area at mile 207 (west of Missoula). In Wyoming, the Greybull Rest Area (mile 480) has clean facilities. Consider an overnight stay in Missoula or Butte to break the journey. Stretch your legs at scenic viewpoints like the Homestake Pass overlook.

Things to do between Coeur d'Alene, ID and Thermopolis, WY: Besides the mentioned stops, try whitewater rafting on the Lochsa River near Kooskia, ID (detour off US-12). In Montana, visit the Montana Vortex near Columbia Falls for a quirky optical illusion experience. For a truly hidden gem, seek out the Pompeys Pillar National Monument (east of Billings, MT) featuring the signature of William Clark (of Lewis & Clark fame)—a two-hour detour from the main route but well worth it.

Finally, for those looking to maximize their journey, refer to how to find the best stops and hidden gems between cities for expert tips on curating your adventure.