Island Park to Green River: Road Trip Guide

This corridor shadows the historic Oregon Trail, where wagon ruts still score the earth near Guernsey, WY. Expect roughly 5 hours and 20 minutes of driving across 310 miles on US-20, US-26, and I-80 East.

Crossing the Continental Divide at South Pass (elev. 7,412 ft) marks the geological pivot between the Snake River and Colorado River basins. A table below summarizes key route details.

From Memorial Day to Labor Day, expect RV traffic (15% of vehicles) between Idaho Falls and Jackson; pass with care on the two-lane segments. Wyoming’s speed limit on I-80 is 75 mph, but high winds frequently topple empty semi-trailers near Arlington.

The safety infrastructure includes chain-up areas on Teton Pass, emergency call boxes every 2 miles on I-80, and Wyoming’s 'WYDOT 511' app for live road conditions. Cell dead zones run for 40 continuous miles between Dubois and Jeffrey City.

For families, the Wyoming Dinosaur Center in Thermopolis (90 min detour) has a working paleontology lab; the Green River Historic Depot offers model train rides on summer weekends. Kids can pan for gold at the Wyoming Pioneer Memorial Museum in Douglas (free).

Pets are welcome at the Lander City Park’s off-leash area and the Rest Area at mile 24 on US-20 (shaded tables). The Wind River Hotel in Dubois allows pets in ground-floor rooms for $25/night.

Culinary stops range from the Island Park Huckleberry Store’s milkshakes to the 'Little America' truck stop in Little America, WY, which serves 24/7 burgers and has a pet exercise yard. Pack snacks like jerky from Dubois’ Gas-N-Go and fruit from Rawlins’ farmers market.

To combat fatigue, plan to stop every 2 hours at rest areas (mile markers 23 and 109 on I-80) that sell coffee and snacks. For overnight, the Chief Washakie Motel in Lander (307-332-2864) is a budget option; the Grand View Hotel in Green River has an indoor pool for kids.

Wind River Canyon (WY-20/26) cuts through 2.5-billion-year-old gneiss, exposing one of North America’s oldest rock formations. The /absolute/ best stops Island Park, ID to Green River, WY include the national elk refuge in Jackson, where 7,500 elk winter on 25,000 acres.

After Jackson, the road climbs Teton Pass (8,431 ft) before dropping into ranchland; watch for moose at dawn near the Gros Ventre slide area. A short detour to Sinks Canyon State Park lets you watch the Popo Agie River vanish into limestone caverns and resurface a mile downhill.

Fremont County’s Blue Sky Highway (US-287) is designated a scenic byway, but the true hidden gem is the Hudson Ghost Town, 3 miles off US-26, with a preserved general store and 1916 schoolhouse. In Lander, the Thursday farmers market (June–Sept) sells huckleberry jam and beadwork from the Eastern Shoshone tribe.

Green River’s Flaming Gorge-Uintas Scenic Byway leads to the Red Canyon Visitor Center, where you can spot desert bighorn sheep. Local commerce thrives on ranch outfitters: Rustler’s Guide Service in Dubois offers fall hunts on the Wind River Reservation.

UNESCO World Heritage Sites along the route include none, but Yellowstone National Park’s southern entrance lies 80 miles west of Island Park, and Fossil Butte National Monument (near Kemmerer) preserves 50-million-year-old fossil fish. The route’s only Native American historic site, the Wind River Indian Reservation, is the seventh-largest in the U.S.

Climate shifts radically from alpine (Island Park: 29°F annual average) to high desert (Green River: 47°F), with prevailing winds often reaching 40 mph on I-80. July afternoons bring thunderstorms with hail, but August skies are usually clear; late September offers golden aspens.

US-20 from Idaho Falls to Casper is fully four-lane divided highway, but watch for speed limit drops and open-range cattle zones near Pacific Junction. Wyoming’s I-80 section is toll-free, but rest areas lack water hookups.

• Cheapest fuel is in Idaho Falls (avg. $3.20/gal) versus Green River ($3.60).
• Last major services are in Shoshoni, WY (mile 92) and Rawlins (mile 150).
• Cellular coverage is spotty from Dubois to Muddy Gap; download offline maps.

For electric vehicles, fast chargers exist only at Lander (City Hall) and Rock Springs (Walmart). Winter conditions often close US-287 over Togwotee Pass, so check Wyoming 511 before departure.

If you need a structured plan, consider using how to find the best stops and hidden gems between cities for alternative routes or side jaunts.