Gardiner to Keystone Road Trip: Scenic Stops Guide

Starting in Gardiner, Montana—the only year-round entrance to Yellowstone National Park—the drive to Keystone, South Dakota covers approximately 500 miles through some of the most iconic landscapes in the American West. The route follows US-191 South to I-90 East, passing through Wyoming and into South Dakota, with the Black Hills as your final destination.

The journey crosses the Continental Divide twice, traverses high plains and mountain passes, and ends near Mount Rushmore, a UNESCO World Heritage Site (though Mount Rushmore itself is not; the listing refers to the nearby Crazy Horse Memorial? Actually, neither is on the list; the only UNESCO site in the region is Yellowstone, which you leave behind). For a detailed breakdown of how to find the best stops and hidden gems between cities, check out this guide.

The route begins amidst Yellowstone's geothermal features, then descends into the Bighorn Basin, known for its dinosaur fossils. You'll pass the Bighorn Mountains, the Powder River Basin, and the Black Hills, which are sacred to the Lakota people. The name "Keystone" evokes the mining history, now a tourist hub.

Local commerce along the way includes Western-themed towns like Buffalo, Wyoming, where you can find handmade crafts. Near the end, in the Black Hills, you'll encounter roadside attractions like Reptile Gardens and Bear Country USA. The region's culinary scene offers buffalo burgers, and in Keystone, you can find homemade fudge.

The primary route is US-191 South to I-90 East, then US-16 South to Keystone. The interstate portions are well-maintained, but mountain passes can be challenging in winter. Fuel stops are sparse in Wyoming; plan to fill up in Gardiner, Cody, Buffalo, and Rapid City.

• Distance: 491 miles (790 km) via I-90 and US-16.
• Estimated driving time: 8–9 hours without stops.
• Best time to drive: Late spring to early fall for road conditions.

The route includes two-lane highways with potential wildlife crossings, so be alert, especially at dawn and dusk. Rest areas are available at intervals; plan to stop every 2 hours. The speed limit on I-90 is 80 mph in South Dakota, but lower in construction zones.

For families, the route offers child-friendly stops like the Wyoming Dinosaur Center in Thermopolis. Many rest areas have pet exercise areas, but pets are not allowed on trails in national parks. Fatigue is a risk; use designated rest zones and consider an overnight stay in Buffalo or Rapid City.