McCall to Rock Springs Road Trip: Idaho Scenic Drive Guide

Did you know that the stretch of US-20 between Fairfield, ID and Mud Lake, ID is known as the "Craters of the Moon Highway," named after the adjacent national monument that was once used as a training ground for Apollo astronauts? This road trip from McCall, Idaho to Rock Springs, Wyoming covers approximately 450 miles and takes about 6 hours of pure driving time. However, with recommended stops, plan for 8-10 hours to fully experience the unique geology and small-town charm. The route begins at Payette Lake in McCall (elevation 5,010 ft) and ends at the high desert of Rock Springs (elevation 6,240 ft), crossing three time zones—though only the Mountain Time Zone change occurs near the Wyoming border.

For an in-depth guide on how to find the best stops and hidden gems between cities, check out this article. This trip showcases Idaho's volcanic landscapes, the Snake River Plain, and Wyoming's Red Desert. The best time to drive is late spring through early fall, as winter storms can close passes like Teton Pass (if detouring) or US-20 near Dubois. Summer temperatures range from 80°F in valleys to 60°F at higher elevations. This guide covers every detail from fuel logistics to pet-friendly parks, ensuring you don't miss the surreal volcanic craters or the best pie in Arco.

The journey transitions from dense pine forests to stark volcanic badlands. Leaving McCall, you descend along the Payette River through Boise National Forest. Near Fairfield, the landscape opens to sagebrush steppe with distant mountain views. The centerpiece is Craters of the Moon National Monument and Preserve (Mile 200), a 750,000-acre expanse of lava flows, cinder cones, and spatter cones. This is a UNESCO World Heritage candidate (on the tentative list as part of the Snake River Plain volcanic field). Walk the Devil's Orchard Nature Trail or drive the 7-mile Loop Road. Local commerce thrives on agritourism: look for farm stands selling huckleberries (McCall), potatoes (Mud Lake), and Wyoming's famous jade (Rock Springs). The small town of Arco claims to be the first community lit by nuclear power (from the nearby Idaho National Laboratory). Don't miss the 'Experimental Breeder Reactor I' museum, a National Historic Landmark.

Hidden Off-Route Spots

• Bruneau Dunes State Park (40 miles south of I-84): sand dunes 470 ft high
• City of Rocks National Reserve (40 miles south of I-84): granite spires popular with climbers
• Little City of Rocks (east of Gooding, ID): volcanic tuff formations

Road quality is generally good, but watch for wildlife—mule deer and pronghorn antelope frequently cross US-20 especially at dawn and dusk. Ruts on two-lane sections can cause you to drift; always stay alert. Family-friendly stops include the Idahome (a rest area near Atomic City with a nuclear-themed playground) and the Wyoming Dinosaur Center (50 miles off-route in Thermopolis). For kids, the Lava Flow Campground at Craters of the Moon offers a junior ranger program. Pet-friendly framework: most rest areas have pet waste stations, but Craters of the Moon National Monument restricts pets on trails—only allowed on paved paths and in campgrounds. Designated rest zones every 50-60 miles: Fairfield rest area (Mile 110), Arco rest area (Mile 240), and Heise Bridge rest area (Mile 280). For fatigue management, the Idaho Falls Greenbelt (Mile 310) provides a safe walking path along the Snake River. Local culture is tied to farming and mining; the annual Rock Springs International Friends Day (August) honors the town's diverse immigrant heritage.

The primary route uses US-95 south from McCall to I-84 east, then US-26/US-20 east to Rock Springs. For a more scenic bypass, consider Idaho State Highway 75 (Sawtooth Scenic Byway) to Ketchum, then east on US-20. This adds 45 minutes but offers views of the Sawtooth Range. Fuel stations are sparse in central Idaho—plan to fill up in McCall, Fairfield, Arco, and Idaho Falls (the last major town before Rock Springs). Expect gas prices 10-15% higher than national average. All roads are paved and well-maintained, but US-20 between Arco and Idaho Falls is a two-lane highway with passing lanes every few miles.

• Distance: 450 miles (720 km) via US-20
• Driving time: 6 hours without stops; 8-10 hours with stops
• Fuel stops: McCall, Fairfield (Mile 110), Arco (Mile 240), Idaho Falls (Mile 310)
• Road conditions: Check Idaho 511 and Wyoming 511 for winter closures
• Cell service: Spotty from Fairfield to Arco; improved near towns