Pullman WA to Thermopolis WY: Scenic Road Trip Guide

The 585-mile drive from Pullman, Washington, to Thermopolis, Wyoming, crosses the Palouse's rolling wheat fields, the Clearwater River canyon, and the Bighorn Basin's badlands. US-195 to I-90 then I-25/US-20 forms the backbone, with an estimated 9 hours and 15 minutes of pure driving time, not counting stops.

This route loosely follows the path of the Nez Perce Trail, and near Thermopolis, the world's largest mineral hot spring—the Hot Springs State Park—has drawn travelers for over a century. The drive climaxes with a dip in the 104°F waters of the state-run bathhouse.

Before you go, consider how to pace your trip: it's a journey of contrasts, from arid sagebrush to pine forests, with quirky roadside attractions and family-friendly diversions along the way. The following guide details the logistics, landmarks, and practicalities to make the most of this cross-country adventure.

From Pullman, take US-195 south to Lewiston, Idaho, then US-12 east to Missoula, Montana, where you'll pick up I-90. At Billings, switch to I-90 south to Columbus, then US-212 west to Belfry, Montana, finally meeting US-20 in Cody, Wyoming, which leads directly to Thermopolis. This routing avoids the congested I-84 corridor and offers smoother pavement on the Montana sections.

Road quality is generally good, with the majority of the route being divided highways. Expect mountain passes like Lookout Pass (elev. 4,730 ft) and the Beartooth Highway (US-212) if you choose the scenic alternate, but the default route via I-90 is all-weather, maintained year-round. No tolls are encountered on this itinerary.

Fuel and Route Economics

Fuel stops are plentiful along I-90, with major towns every 40-60 miles. In the more remote stretches of Montana and Wyoming, plan to fill up where fuel is available: Look for stations in Missoula, Bozeman, Billings, and Cody. Gas prices tend to be lower in Montana than in Washington, but higher in Wyoming's tourist towns like Cody.

• Average fuel cost for a mid-size car: $85–$110 (at $3.60–$4.20 per gallon).
• Most expensive fuel: Pullman and Cody.
• Cheapest fuel: around Butte, Montana.

Budget for meals: roughly $15–$25 per person for sit-down restaurants; fast food chains are available in most towns. Overnight lodging ranges from $80 (motels) to $200+ (resorts in Cody).

Natural Attractions and UNESCO Heritage

The route never directly accesses a UNESCO World Heritage Site, but Yellowstone National Park, a UNESCO site, lies just 90 miles south of the route's midpoint via US-14. If you have spare time, a detour to the park's Lamar Valley offers wildlife viewing and geothermal features, but this adds at least 3 hours round-trip. Near Thermopolis, the Hot Springs State Park is a National Historic Landmark (the bathhouse) and natural wonder, featuring terraced travertine formations.

Key scenic landmarks include the Palouse Falls (a 198-ft waterfall in Washington, a detour off US-195 via SR-26), the Little Bighorn Battlefield National Monument (off I-90 at Crow Agency, MT), and the Bighorn Canyon National Recreation Area south of Lovell, WY. These are all easily reached from the main route and reward travelers with stunning geology and history.

Local Commerce and Culture

The route passes through towns with distinct personalities: Lewiston's riverfront, Missoula's university vibe, Bozeman's craft breweries, Billings' Western heritage, and Cody's Old West shows. In Thermopolis, the local economy centers on the hot springs and the Wyoming Dinosaur Center, which features real excavation sites. Farmers' markets operate in summer in Missoula and Bozeman, offering local produce, crafts, and food trucks.

Indigenous culture is visible through the Nez Perce National Historical Park sites in Idaho and the Crow and Northern Cheyenne reservations in Montana. Respect tribal lands by researching access rules. For a taste of local flavor, try huckleberry products in Montana, bison burgers in Wyoming, and Palouse lentils back in Washington.

Infrastructure Safety and Driving Conditions

Interstate and US highways are well-signed; speed limits range 70–80 mph on interstates (MT may allow up to 80), with lower limits through towns. Watch for deer and elk, especially at dawn/dusk, and in Wyoming, antelope. Winter travel can bring snow and ice, particularly over Lookout Pass and in Wyoming; check forecasts and carry chains (legally required in some passes) from October to May. Mobile coverage is spotty in Montana's mountain stretches; download offline maps.

Emergency services are available in all towns, but response times can be 30 minutes in remote areas. Always keep water, snacks, blankets, and a first-aid kit.

Family and Pet-Friendly Framework

Most attractions along the route are family-friendly, and many allow pets on leashes (e.g., Little Bighorn Battlefield, Yellowstone's pullouts). Hot Springs State Park has picnic areas and open lawns; the state bathhouse has separate hours for families. For kids, the Wyoming Dinosaur Center in Thermopolis has interactive exhibits and fossil prep labs. Restaurants generally have high chairs and kids' menus, but calling ahead is wise in small towns.

For pets, most motel chains are pet-friendly; note that some national parks (Yellowstone) restrict pets on trails. Carry vaccination records and waste bags. Rest stops with pet areas are common on interstates.

Fatigue Management and Rest Zones

Long drives require planned breaks. Schedule rest stops every 2-3 hours: major rest areas are at Coeur d'Alene, ID (westbound), and in Montana at Bozeman and Billings. Quirky stops to break monotony: the 'Intermountain' rest area near Logan Pass (no, not on route) – instead, the Bearmouth Rest Area (I-90 east of Missoula) offers scenic views. For extended breaks, consider a short hike at Pictograph Cave State Park near Billings (5 miles off I-90) or a walk around the hot springs at Thermopolis.

• Use the 'Drive Alert' phone app to warn you of drowsiness.
• If tired, pull into a well-lit truck stop or motel to nap.
• Caffeine is not a substitute for sleep; alternate drivers if possible.

For hidden gems, learn how to find the best stops and hidden gems between cities using local insights and satellite imagery.