Sun Valley to Buffalo: Epic Road Trip through Wyoming

The drive from Sun Valley, Idaho to Buffalo, Wyoming follows US-20 east, then I-15 south, and finally I-80 east to exit 56, joining US-16 north. This 550-mile journey crosses the North American continental divide at an elevation of 7,000 feet near Togwotee Pass. The route passes through a geologic unconformity where 2.5-billion-year-old Precambrian granite meets 500-million-year-old Paleozoic sedimentary layers exposed in the Wind River Canyon.

Estimated driving time is 9 to 10 hours without stops. Key highways include US-20, I-15, I-80, and US-16. The most efficient route is: Sun Valley → Idaho Falls (US-20) → I-15 south to I-80 east → exit 56 to US-16 north to Buffalo.

For advice on uncovering lesser-known attractions, check how to find the best stops and hidden gems between cities.

Road quality is excellent on interstates, but US-20 from Sun Valley to Idaho Falls has occasional sharp curves. Winter conditions can be severe; check weather for Togwotee Pass. No UNESCO sites direct on route, but nearby Yellowstone National Park (UNESCO) is 100 miles northwest of Buffalo.

• Family-friendly stops: Heise Bridge crossing over South Fork of the Snake River (picnic area), Bear Lake State Park (beach and swimming), Little America (restaurant and store).
• Pet-friendly framework: Most rest stops allow pets on leash; hotels in Idaho Falls (La Quinta) and Rawlins (Super 8) accept pets.
• Fatigue management: Stop every 2 hours or 150 miles. Recommended stops: milepost 306 on US-20 (Hamer), milepost 104 on I-80 (Green River), milepost 211 (Rawlins).

Fuel stations are plentiful along I-15 and I-80, but sparse east of Rock Springs, WY. Plan refueling in Idaho Falls, Pocatello, Rock Springs, and Rawlins. Average gas price along the route is $3.50 per gallon. Total fuel cost for a 550-mile trip in a 25 mpg vehicle is approximately $77.

• Best fuel stops: Idaho Falls (many options), Rock Springs (Chevron at exit 104), Rawlins (Pilot at exit 211).
• Electric vehicle charging: Level 3 chargers in Idaho Falls (Electrify America), Rock Springs (Tesla Supercharger), and Rawlins (ChargePoint).
• Rest areas: Heise Rest Area (milepost 301 on US-20), Bear Lake Rest Area (I-15 mile 6), Little America Rest Area (I-80 mile 124).

The route offers extraordinary geological diversity: from the volcanic basalt plains of the Snake River Plain to the alpine peaks of the Wind River Range. The historic Union Pacific Railroad parallels much of I-80, a reminder of the 1869 transcontinental railroad heritage.

• Natural attractions: Craters of the Moon National Monument (near Arco, ID), Bear Lake (on the ID-UT border), Flaming Gorge National Recreation Area (near Vernal, UT), Wind River Canyon (Wyoming).
• Cultural commerce: Idaho Falls has a thriving downtown with local artisans; Rawlins offers the Wyoming Frontier Prison Museum; Buffalo is known for the Occidental Hotel.
• Things to do: Hike the Fossil Butte National Monument near Kemmerer, WY; visit the Green River Rendezvous in Pinedale (summer).