Monticello to Thermopolis: Utah to Wyoming Road Trip Guide

This 400-mile route from Monticello, UT to Thermopolis, WY climbs from the Colorado Plateau at 7,000 feet to the Bighorn Basin, passing through two national parks, a national recreation area, and a UNESCO World Heritage Site. The drive takes roughly 7-8 hours without stops, but plan for at least two days to experience the landscapes. A little-known detail: near Vernal, UT, the highway crosses the 40th parallel north, an invisible line that also runs through Madrid, Spain and Beijing, China.

How to find the best stops and hidden gems between cities – our guide to off-route discoveries.

Arches and Canyonlands (Moab Area)

Just 50 miles north of Monticello, Moab is the gateway to two national parks. Arches National Park features over 2,000 natural stone arches, including Delicate Arch. Canyonlands: Island in the Sky district offers sweeping views of the Colorado River canyon. Both require timed entry reservations in peak season (March–October).

• Entry fee: $30 per vehicle per park. Annual pass accepted.
• Best hike: Delicate Arch (3 mi round trip).
• Local commerce: Moab's Main Street has gear shops, cafes, and bike rentals.

Flaming Gorge National Recreation Area (Utah/Wyoming border)

This red-rock canyon reservoir offers boating, fishing, and scenic drives. The Flaming Gorge Dam Visitor Center explains the geology. The drive along the gorge on US-191 is breathtaking, with pullouts for photos. Stop at the Sheep Creek Geological Loop (auto tour) near Manila, UT.

• Entry fee: $5 per vehicle (or interagency pass).
• Activities: boat rentals, hiking, wildlife viewing (bighorn sheep, golden eagles).
• Best view: Red Canyon Overlook.

UNESCO World Heritage Sites: Dinosaur National Monument

Near the Utah-Colorado border, this monument preserves a dinosaur fossil quarry with over 1,500 bones embedded in the rock. The Quarry Exhibit Hall allows visitors to see the wall of bones. It's a 45-minute detour east of Vernal on US-40. The site is a UNESCO World Heritage Site (part of the “Jurassic” designation).

• Entry fee: $25 per vehicle.
• Tip: Visit the park's scenic drive along the Green River for canyon views.

Thermopolis Hot Springs State Park

End the trip at the world's largest mineral hot spring, pouring 3.6 million gallons of 104°F water daily. The State Bath House offers free public soaking (limited hours). For a private experience, try the Star Plunge or Hot Springs County Water Park. The park also has bison and a suspension bridge.

• Free bath house hours: check state park website.
• Local commerce: Thermopolis has diners, a brewery, and a river walk.

Hidden Off-Route Spots

Between Moab and Green River, take the turnoff for the “Goblin Valley State Park” detour (adds 1 hour). Alternatively, near Rock Springs, visit the “White Mountain Petroglyphs” – ancient rock art accessible via a short hike. These spots are less crowded and offer unique photo ops.

• Goblin Valley: entry $20. Best at sunrise for lighting.
• Petroglyphs: free, easy access, but carry water.

Family and Child Suitability

The route is suitable for families with children, especially with stops at Dinosaur National Monument and Flaming Gorge. In Moab, children enjoy the “Museum of Moab” and easy hikes like Park Avenue in Arches. Thermopolis's hot springs are a hit with all ages. Carry snacks and water; restaurant options in small towns (Manila, WY) are limited.

• Restrooms: available at visitor centers, gas stations, and state parks every 50-80 miles.
• Stroller-friendly: paved paths at Flaming Gorge Dam and in Thermopolis state park.

Pet-Friendly Framework

Pets are allowed on paved roads in national parks but not on trails. Flaming Gorge allows leashed pets in most areas. In Thermopolis, pets are prohibited in the indoor pools but can walk on park grounds. Many motels in Moab and Rock Springs accept pets for a fee. Always carry water and waste bags.

• Pet-friendly lodging: La Quinta in Moab, Best Western in Rock Springs.
• Veterinary clinics: Moab (24-hr animal ER), Vernal, and Rock Springs.

Fatigue Management and Rest Zones

Long stretches between towns can induce fatigue. Plan rest stops every 2 hours. Recommended break points: Moab (lunch, stretch), Green River (fuel, snacks), Rock Springs (coffee, walk around). Rest areas exist on I-80 near Rock Springs with picnic tables. In the mountains, pullouts allow short walks.

• Rest areas: milepost 128 on I-80 (WY), and at Flaming Gorge overlooks.
• Alternative: nap in a rest stop (use an alarm).

Local Commerce and Culture

Moab's economy is tourism-driven; buy local art on Main Street. In Vernal, the “Utah Field House of Natural History” includes a dinosaur garden. Rock Springs has a historic downtown with the “Rock Springs Historical Museum.” Thermopolis hosts the “Wyoming Dinosaur Center” with a working dig site. For souvenirs, look for local honey, jams, and sandstone sculptures.

• Farmers markets: Moab Saturday mornings (May-October).
• Dining: try a bison burger in Thermopolis or fry sauce in Utah.

Fuel and Route Economics

Gas stations cluster around towns: Monticello, Moab, Green River, Vernal, Rock Springs, Rawlins, and Thermopolis. Prices vary; fill up in Rock Springs for cheaper fuel. Diesel is widely available. Electric vehicle charging stations exist in Moab, Green River, and Rock Springs (Level 2 and some DC fast chargers).

• Monticello to Moab: US-191 N, 50 miles, 55 min. No services between.
• Moab to Vernal: US-191 N then US-40 E, 150 miles, 2.5 h. Stop at Green River for gas.
• Vernal to Rock Springs: US-191 N, 120 miles, 2 h. Sparse services after Manila.
• Rock Springs to Thermopolis: I-80 W then US-191 N through Rawlins, then US-20 W, 140 miles, 2.5 h.

Road Quality and Safety

US-191 is generally well-paved but narrow in sections through the Ashley National Forest. I-80 is a divided highway. Watch for wildlife (deer, elk) near dawn/dusk, especially through Flaming Gorge. Winter travel requires snow tires; summer brings afternoon thunderstorms. Cell service is intermittent between Moab and Green River, and between Vernal and Rock Springs. Download offline maps.

• Road construction season: May–October. Check UDOT and WYDOT for delays.
• Speed limits: 65-70 mph on US highways, 80 mph on I-80 in Wyoming.