Island Park to Pierre: A Practical Road Trip Guide

The drive from Island Park, Idaho, to Pierre, South Dakota, covers roughly 670 miles and takes about 10 hours of pure driving, but the journey crosses the Continental Divide and the Missouri River, offering a shifting tapestry of mountain, prairie, and river landscapes.

This route follows US-20 east to Idaho Falls, then I-15 north to I-90 east through Montana and Wyoming, before heading south on US-85 to Pierre. It's a corridor rich in history, from the Oregon Trail to the Lewis and Clark expedition.

Here's a practical guide to making the most of this cross-country drive.

Total distance: ~670 miles

• Driving time: ~10 hours without stops
• Recommended: 2 days with an overnight in Buffalo or Gillette

The drive passes through three distinct geological provinces: the volcanic Yellowstone Plateau, the Rocky Mountains, and the Great Plains. You'll see dramatic changes from pine forests to sagebrush steppe to rolling grasslands.

A must-see is the how to find the best stops and hidden gems between cities guide, which offers strategies for uncovering roadside attractions.

In Buffalo, Wyoming, the historic Occidental Hotel (circa 1880) is a great place to stretch your legs and grab a meal. For a taste of local commerce, stop at the farmer's market in Bozeman if you're traveling in summer.

The route is generally safe, but watch for wildlife, especially deer and elk, particularly at dawn and dusk. In winter, carry emergency supplies and check forecasts.

For families, consider a stop at the Wyoming Dinosaur Center in Thermopolis (a slight detour) or the Journey Museum in Rapid City. For pets, many hotels are pet-friendly, but always confirm in advance.

Fatigue is a real concern on long stretches. Rest areas are plentiful along interstates, but on US-85, plan to stop at small towns like Lusk and Kadoka. Aim to stop every 2 hours to stay alert.

• Rest stops: Every 50-100 miles on interstates
• Food options: Fast food and diners in towns, limited on rural stretches
• Unique spot: The 1880 Town near Kadoka is a quirky roadside attraction

Fuel prices vary significantly along the route; plan to fill up in larger towns like Idaho Falls, Buffalo, and Gillette, where prices are often lower than in rural areas. Gas stations become sparse across Wyoming, so don't pass up a chance to refuel when below half a tank.

The route is well-maintained, with interstate highways for most of the way, except for the final stretch on US-85 from I-90 to Pierre, which is a scenic two-lane road through badlands and ranchland.

• Interstates: I-15, I-90
• US Highways: US-20, US-85
• Road conditions: Check Wyoming DOT alerts for winter closures