Sun Valley to Kemmerer: A Scenic Idaho-Wyoming Road Trip

This 210-mile route from Sun Valley, Idaho, to Kemmerer, Wyoming, follows US-30 and ID-75 through the Snake River Plain and the Caribou-Targhee National Forest. The drive typically takes 3.5 to 4 hours without stops, but you'll want to linger. A little-known fact: the route roughly parallels the historic Oregon Trail near the Portneuf River, where wagon ruts are still visible.

Before you head out, check if there are any road works—ID-75 can have temporary closures near Picabo. For deeper insights on planning, see how to find the best stops and hidden gems between cities.

The route crosses the Portneuf Valley, a broad basin flanked by the Bannock Range and the Portneuf Mountains. Just north of Lava Hot Springs, the old Union Pacific railroad grade runs parallel to the highway—ideal for a short walk.

Natural Landscapes & Attractions:

• Craters of the Moon National Monument (detour via US-20/26/93, add 1 hour) – lava flows and caves
• Portneuf River Canyon (just west of Lava Hot Springs) – hiking and fishing
• Bear Lake (south of US-30 on ID-30) – turquoise water, 30 min detour

Fuel and Route Economics: Gas is cheapest in Pocatello. Use GasBuddy to find stations. If driving from Sun Valley to Kemmerer, Wyoming, know that Wyoming has lower fuel taxes but fewer stations. Carry extra water and snacks.

UNESCO World Heritage Sites: None directly on route, but the nearby Yellowstone National Park (~4 hours north) is a UNESCO site. For the road, consider the Jurassic National Monument (near Kemmerer) which houses the world's best-preserved fossil fish.

Climatic Conditions & Route Aesthetics: Summer: 80-90°F, dry, with occasional thunderheads. Autumn: golden aspen and cool air. Winter: snow possible ID-75; carry chains. Spring: wildflowers in the Portneuf hills.

Culinary Infrastructure: Best stops: Sun Valley (The Kneadery for breakfast), Lava Hot Springs (The Lava for burgers), Pocatello (Buddy's Italian for pizza), Kemmerer (Fossil Fish Grill for trout). For picnics, buy supplies at Broulim's in Sun Valley or Pocatello's WinCo.

Gas stations are sparse between Carey and Arimo. Fill up in Sun Valley (premium fuel recommended for high altitude) and again in Pocatello. The best diesel prices are often at the Sinclair station on US-30 in Lava Hot Springs. Cell coverage is unpredictable—AT&T and Verizon work in towns but drop in the mountains. Carry a physical map or offline GPS.

• Estimated total fuel cost: $25-$35 (mid-grade, 25 mpg)
• Road condition: Mostly good asphalt with some gravel access roads near national forest
• Elevation: Sun Valley at 5,920 ft; Kemmerer at 6,934 ft; passes up to 7,200 ft

Family and Child Suitability: The Lava Hot Springs Aquatic Center offers three natural hot springs pools perfect for kids. Bison Range Overlook on US-30 near Soda Springs is a safe spot to see wildlife. Bring car games for the long stretch between Arimo and McCammon.

Pet-Friendly Framework: Most hotels in Kemmerer and Lava Hot Springs allow pets. Rest stops like the one at milepost 32 on US-30 have grass areas. Keep dogs leashed near livestock.

Infrastructure Safety & Road Quality: ID-75 is two-lane with light traffic; use caution at night for deer. US-30 is well-maintained with rumble strips on shoulders. Check Idaho 511 for road alerts.

Hidden Off-Route Spots: Soda Springs Geyser (only captive geyser in the US) – an easy 5-min detour. Harriman State Park (west of US-20) – for moose and trumpeter swans, but adds 40 min.

Fatigue Management & Rest Zones: Scheduled rest areas at Portneuf Valley (US-30, milepost 28) and Pocatello (I-15 exit 69). Plan to swap drivers every 2 hours. If tired, stop at the gas station in McCammon for coffee.

Local Commerce & Culture: Lava Hot Springs has a quaint downtown with artisan shops. Pocatello's Museum of Clean is a quirky family stop. Kemmerer's Fossil Butte National Monument visitor center educates about the Green River Formation.