Bismarck to Afton Road Trip: Epic Drive through Plains & Tetons

The drive from Bismarck, ND to Afton, WY covers roughly 750 miles along US-85 and I-90 West, crossing three time zones and the Missouri River headwaters. This route passes through the Little Missouri National Grassland and the Bighorn Mountains, offering a transition from Great Plains to Rocky Mountain landscapes. One quirky milestone: near Belle Fourche, SD, you'll find the geographic center of the United States (including Alaska and Hawaii), marked by a small monument.

How long to drive Bismarck, ND to Afton, WY? Without stops, expect 12–13 hours of driving time. However, with recommended breaks and attractions, most travelers take 2–3 days. Is it worth driving Bismarck, ND to Afton, WY? Absolutely, for the dramatic scenery, historic sites, and quiet rural roads. For maximizing your experience, see how to find the best stops and hidden gems between cities.

Road hazards include wildlife (deer, antelope, and cattle on open range), especially at dawn/dusk. Wyoming permits texting while driving only with hands-free devices. Speed limits: 65–80 mph; enforced by radar in small towns.

• Winter safety: I-90 closures common east of Buffalo. Check WYDOT cameras. Carry blankets, water, and a shovel.
• Family stops: Reptile Gardens (Rapid City), Storybook Island (Rapid City), and the Children's Museum of Northern Wyoming (Buffalo).
• Pet-friendly: Most motels in Spearfish and Buffalo allow pets ($20 fee). Rest stops with pet areas every 50 miles.

Fatigue management: Plan to stop every 2 hours. Recommended rest zones include the Flying J in Spearfish (mile 170), the rest area at Powder River Pass (mile 350), and the Shoshoni Municipal Park (mile 500).

Hidden off-route spots: The Vore Buffalo Jump (south of I-90, exit 187) – a natural buffalo kill site used by Plains Indians. Free admission. Another: the Hogback Bridge arch near Ten Sleep.

The route showcases three distinct eco-regions: the Missouri Plateau (badlands in Theodore Roosevelt NP), the High Plains (grasslands and agriculture), and the Bighorn Basin (desert-like canyons). South of Spearfish, the Black Hills rise abruptly, covered in Ponderosa pine and granite spires.

• Theodore Roosevelt National Park (North Unit): Petrified forests, bison herds, and the Painted Canyon Overlook. Off I-94 near Belfield.
• Wind Cave National Park (south of Custer): One of the world's longest caves with boxwork formations. Above ground, prairie dog towns.
• Bighorn National Forest: Cloud Peak Wilderness, alpine meadows, and the Medicine Wheel National Historic Landmark (a pre-Columbian stone circle).

Local commerce leans toward ranching and tourism. In Thermopolis, visit the Wyoming Dinosaur Center with real dig sites. In Afton, explore the Star Valley's Swiss cheese heritage and the LDS temple. Artifacts from the Oregon Trail are visible near Guernsey (Register Cliff).

For souvenirs: Buchanan & Hohlt mercantile in Buffalo (Wyoming's oldest store). Produce stands in Shoshoni sell cherries and apples in August.

The primary route uses US-85 south from Bismarck to I-90 west, then US-16/20 west through the Bighorn National Forest. From Buffalo, WY, take US-16 west over the Powder River Pass (elevation 9,666 ft) to Ten Sleep, then onto US-20 west through Shoshoni and Thermopolis. Finally, take US-26 west to WY-237 south into Afton.

• Road quality: Well-paved highways; occasional construction in summer. US-16 over the Bighorns has sharp curves.
• Fuel stops: Every 30–50 miles along interstates; sparse in Wyoming between Shoshoni and Afton (90-mile gap). Refuel at Lusk, Lingle, or Douglas.
• Cell service: Spotty in Bighorn National Forest and rural Wyoming. Download offline maps.

Drive time includes three major passes: the Bighorns, Powder River, and the Salt River Range. Winter travel (Nov–Mar) requires snow tires and chains. Summer sees heavy RV traffic in July.

Total estimated fuel cost: $150–$200 (gas at $3.50/gal, 20 mpg). Tolls: none. Parks entrance fees: $35 for Wind Cave, $35 for Devils Tower (if detoured).