Big Sky to Keystone Road Trip Guide: Scenic Drive

Big Sky, MT sits at an elevation of 7,500 feet, and Keystone, SD is at 4,100 feet. This 490-mile route descends through the Gallatin National Forest, crosses the Continental Divide, and skirts the Black Hills. The drive takes about 8 hours without stops, but you'll want at least two full days to explore.

The route follows US-191 south to I-90 east, then US-16 east into South Dakota. A notable geographic quirk: you'll cross the continental divide twice—once at Targhee Pass (elevation 7,072 ft) and again near the Wyoming border. The plains between are a study in open space.

How to find the best stops and hidden gems between cities is a Wayro article that helps pinpoint obscure attractions along this corridor.

Road quality is mostly excellent. US-191 between Big Sky and Bozeman has sharp curves and occasional wildlife (deer, elk). I-90 is well-maintained in Montana and Wyoming, but watch for potholes in spring. South Dakota's portion of I-90 is smooth.

Family suitability: The drive is long for young children. Plan stops every 2-3 hours. Attractions like the Bozeman Children's Museum, the Hot Springs at Chico (south of Livingston), and Mount Rushmore are kid-friendly. In Keystone, the Rushmore Tramway Adventures offers rides.

Pet-friendly framework: Most truck stops and rest areas allow pets on leashes. Big Sky has several pet-friendly lodges. In the Black Hills, pets are allowed in Custer State Park with restrictions. Keep dogs leashed due to wildlife.

Fatigue management: Stretch legs at rest areas near Three Forks (MT), exit 274 I-90; and at the Powder River Rest Area (WY) exit 126. Consider an overnight halfway, like in Buffalo, WY, which has multiple motels. Use cruise control on straight stretches but stay alert for crosswinds.

• Safety Tips: Carry a first-aid kit, warn for construction on I-90 near Sheridan (summer 2024), and watch for deer at dusk.
• Hidden Off-Route Spot: The Red Lodge Mt. (MT) via US-212 from I-90 exit 408 is a beautiful detour, but adds 1.5 hours.

The drive starts in the Rocky Mountains, with pine forests and granite peaks. South of Big Sky, you'll see the Gallatin River, famous for fly fishing. As you descend to Bozeman, the mountains give way to the Gallatin Valley, a broad agricultural basin.

On I-90 east of Bozeman, the landscape transitions to high plains. Near Livingston, you'll see the Yellowstone River. The Absaroka Range looms to the south. The stretch from Livingston to Buffalo, WY is dominated by rolling hills and cattle ranches.

In northeastern Wyoming, the terrain becomes arid with sagebrush. The Black Hills are a surprise: a forested uplift rising 3,000 feet above the plains. Approaching Keystone, you'll see granite spires and ponderosa pine forests.

Local commerce is stronger in Bozeman, a college town with craft breweries and outdoor gear shops. Buffalo, WY is a ranching town with classic Western stores. Wall, SD (near I-90) is famous for Wall Drug, a kitschy complex that draws tourists. Keystone is a tourist-focused town with gift shops, taffy stores, and Old West facades.

US-191 from Big Sky to Bozeman is a winding two-lane road through canyon terrain. I-90 east from Bozeman is a four-lane interstate with a 75 mph speed limit. Gas stations are sparse between Bozeman and Buffalo; fill up in Bozeman (regular gas ~$3.50/gal) and again in Buffalo.

For fuel economics, consider using GasBuddy along I-90. The most expensive gas is near Big Sky; prices drop 10-15 cents per gallon in South Dakota. Carry extra water and snacks, as some stretches have no services for 60+ miles.

• Route: US-191 S → I-90 E → US-16 E
• Total Distance: 490 miles
• Driving Time: 7.5-8.5 hours
• Best Time: June to September (snow possible in May/October)

UNESCO World Heritage Sites: Yellowstone National Park is 25 miles south of Big Sky (via US-191) and is a UNESCO site. While it's a detour, many travelers incorporate a visit. The core route itself does not pass through any other UNESCO sites, but the nearby Black Hills National Forest offers historic sites.