Island Park to Custer Road Trip Guide: Best Stops & Tips

Spanning 420 miles across the Rocky Mountains and high plains, the route from Island Park, ID to Custer, SD is a study in contrasts—from the volcanic caldera of Yellowstone to the granite spires of the Black Hills. This journey crosses the Continental Divide at Togwotee Pass (elevation 9,658 feet) and dips into the Wind River Basin before climbing again into the vast expanse of Wyoming's high desert.

Along the way, you'll encounter the historic Oregon Trail at Casper, WY, and the eerie beauty of the Badlands before reaching the storied gold rush town of Custer. This guide condenses the essential logistics, natural wonders, and practical tips for making the most of this scenic and often remote drive.

Starting from Island Park, you'll take US-20 east through Idaho Falls, then pick up I-15 south to I-80 east, passing through Casper, WY. From Casper, US-18/US-20 lead to US-85 northeast, eventually joining US-16 into Custer. This is the most reliable all-weather route, but the more scenic alternative is via US-26 through Dubois and Riverton, then US-287 to Casper.

Fuel stops are sparse in Wyoming, especially between Riverton and Casper (about 100 miles), so plan to fill up whenever you see a station. Gas prices in Wyoming are typically 10-15% lower than in Idaho, but can spike in tourist towns like Buffalo and Custer.

• Major fuel stops: Idaho Falls (ID), Dubois (WY), Riverton (WY), Casper (WY), Buffalo (WY), Sundance (WY), Custer (SD).
• Road quality: I-80 is smooth, but US-26 and US-287 are two-lane highways with occasional potholes; watch for wildlife near dawn and dusk.

This route is largely rural with long stretches without cell service (especially west of Dubois and east of Buffalo). Ensure your vehicle is in good condition, carry a spare tire, and check weather reports—sudden snowstorms can occur even in late spring and early fall. The climate is arid; temperatures can swing 40°F in a single day, so pack layers.

For families, the key stops are the Buffalo Bill Center of the West in Cody, WY (a detour via US-20/US-14/16, about 50 miles off route) and the Bear Country USA wildlife park in Rapid City, SD, just 40 minutes from Custer. Both are highly rated for children.

• Pet-friendly framework: Most motels in Casper and Buffalo allow pets; national forest lands (e.g., Shoshone and Black Hills) allow dogs on trails with a leash.
• Fatigue management: Plan rest stops at Casper, Buffalo, and Newcastle; Wyoming rest areas are well-maintained and often have picnic tables and shade.
• Hidden off-route spot: The Hot Springs State Park in Thermopolis, WY, is a 60-mile detour from Casper and offers free public bathing in the world's largest mineral hot spring.

The route offers a spectacular cross-section of Western landscapes: the volcanic geology of Island Park (known for its rhyolite domes and hot springs), the alpine meadows of the Teton Wilderness, the desert expanses of the Wind River Basin, and finally the granite peaks of the Black Hills. One UNESCO World Heritage Site lies tantalizingly close: Yellowstone National Park, which you can visit by detouring from Island Park via the west entrance—a short 30-minute drive.

Local commerce along the route reflects classic Western towns: Idaho Falls has a thriving farmer's market in summer; Dubois boasts a small museum dedicated to the Mountain Men; Casper offers the National Historic Trails Interpretive Center. To uncover more hidden gems, check out this guide on finding the best stops and hidden gems between cities.