Idaho Falls to Alliance: Wyoming Road Trip Guide

This route from Idaho Falls, ID to Alliance, NE covers approximately 650 miles, crossing the Continental Divide twice – first at South Pass (7,412 ft) in Wyoming, then near Sherman Summit (8,640 ft) – a rare geographic quirk that makes this drive a lesson in basin-and-range topography. The fastest path uses US-20 east to Casper, then I-25 south to I-80 east, arriving in Alliance after about 10–11 hours of driving time.

Unlike the monotony of I-80 across Nebraska, this route delivers surprising diversity: lava fields, high desert plains, red buttes, and the Oregon Trail heritage. To find the best stops and hidden gems between cities, consult our guide on how to find the best stops and hidden gems between cities.

The primary route follows US-20 east from Idaho Falls to just before Casper, then I-25 south to I-80 east. Expect toll-free driving with ample truck stops. Fuel economy: your vehicle will average 22-26 mpg on these highways; plan for 3-4 fuel stops.

• Best gas prices: Rawlins, WY (often $0.10-0.20 cheaper than Idaho Falls).
• EV charging: limited; Level 2 chargers exist in Rawlins and Lusk, WY.
• Road conditions: Generally good pavement; watch for construction west of Rawlins in summer.

Major junctions: US-20/US-26 merge near Shoshoni; I-25 exit 188 (Casper) is critical to stay on course. The route crosses the Oregon Trail multiple times – interpretive signs dot the roadside.

Leaving Idaho Falls, you traverse the Snake River Plain with distant volcanic cones. Near Mud Lake, the sky opens into sagebrush steppe. The climb over the Continental Divide at South Pass is gradual, marked by high desert and antelope herds.

• Must-stop: Red Desert overlook near Wamsutter – a vast basin of striated badlands.
• Hidden gem: Killpecker Sand Dunes (off US-191) – the largest active dune field in North America, accessible via unimproved roads.
• Commerce: Local rancher markets in Lusk, WY sell bison jerky and Rocky Mountain oysters.

Wildlife hazards: Mule deer and pronghorn frequent dawn/dusk hours between Shoshoni and Rawlins. High winds east of Medicine Bow can push empty trailers. Rest areas with RV parking: every 50-70 miles on I-80.

• Family-friendly: Rawlins' Wyoming Frontier Prison offers tours of the old penitentiary.
• Pet stations: Rest areas near Arlington, WY have designated pet exercise areas with shade.
• Fatigue tips: Stop at Walden, CO (via minor detour) to stretch in a pine forest – a surprising change from plains.

For children, the Lincoln Highway markers near Laramie provide a history scavenger hunt. Cell service: AT&T and Verizon work on most of US-20 but drop out between Jeffery City and Lost Cabin.