Rapid City to Idaho Falls: Road Trip Guide

This 600-mile journey from Rapid City, SD to Idaho Falls, ID traverses the Wyoming plains and the Rocky Mountain spine. You'll cross the Continental Divide at 7,013 feet near Togwotee Pass, a boundary where water flows to the Atlantic or Pacific. The route follows I-90 W, US-16 W, and US-20 W, with a total drive time of about 9.5 hours without stops.

Wyoming highways have high speed limits (70-80 mph) but watch for wildlife: mule deer, elk, and occasional moose. Dawn and dusk are most dangerous. The road from Cody to Yellowstone has steep grades and sharp curves; use lower gears on descents. Snow tires required in winter for Togwotee Pass.

• Family stops: The Buffalo History Museum in Buffalo (free for kids under 12). In Cody, the Cody Firearms Museum has interactive exhibits. The Yellowstone Giant Screen Theater shows nature films.
• Pet-friendly framework: Most motels in Buffalo and Cody allow pets (e.g., Super 8 Cody). Yellowstone National Park allows pets on paved roads and in campgrounds but not on trails. Off-leash prohibited.
• Rest zones: I-90 rest area at mile 57 (east of Buffalo) has clean facilities. US-20 rest area near Thermopolis (mile 115) offers picnic tables. The Wapiti Wayside between Cody and Yellowstone has panoramic views.

Fatigue management: Plan stops every 2 hours. The drive across Wyoming's Great Divide Basin can be monotonous; break at the Little Buffalo Historic Site (mile 72 on US-16). For children, pack activity kits and download audiobooks. The route has several 7% grades – use engine braking to save fuel.

After leaving the Black Hills, the landscape opens into the shortgrass prairie of northeastern Wyoming. The geology shifts dramatically near Shell Canyon, where the Bighorn Mountains rise with steep limestone cliffs. The canyon features the Shell Falls at mile marker 18 on US-14, a 120-foot cascade accessible via a short boardwalk.

• Thermopolis: Home to the world's largest mineral hot spring, Hot Springs State Park. Free soaking in the state-run bathhouse.
• Cody: Named after Buffalo Bill Cody, every evening at 8pm the Cody Nite Rodeo runs June-August. The Buffalo Bill Center of the West houses five museums under one roof.

UNESCO World Heritage Sites: None directly on route, but Yellowstone National Park (a UNESCO site) is a 30-minute detour from West Yellowstone. The park's geothermal features and wildlife are quintessential. The road from Cody to Yellowstone via US-14/16/20 (the Wapiti Valley) follows the Shoshone River and offers views of the Absaroka Range.

Local Commerce: In Buffalo, the historic Occidental Hotel (circa 1880) serves as a museum and saloon. In Dubois (on US-26, alternative route), the National Bighorn Sheep Center offers interpretive exhibits. The Wind River Reservation nearby features Native American art and fry bread at the St. Stephen's Mission.

Gas stations are sparse between Buffalo and Cody, especially in the Bighorn National Forest. Fill up in Rapid City, then again in Buffalo. Once you reach Greybull, fuel availability improves. The section from Cody to West Yellowstone has limited services in winter. Plan for tolls: none on this route, but Yellowstone entrance fee ($35 per vehicle) applies. For the best stops and hidden gems, see this guide on finding hidden gems.

• Best gas price periods: small towns like Basin (WY) often cheapest.
• Electric vehicle charging: Rapid City has Tesla Superchargers; Buffalo and Cody have Level 2 chargers. No chargers on US-20 between Cody and West Yellowstone.
• Road conditions: Snow possible from October to May on Togwotee Pass. Check WYDOT app.