Ashton-Flagg Ranch Road / Grassy Lake Road

Ashton-Flagg Ranch Road, also known as Grassy Lake Road by the National Park Service, is a 33-mile scenic backcountry route connecting Ashton, Idaho, to Flagg Ranch, just outside Yellowstone and Grand Teton National Parks. The road travels through remote sections of the Caribou-Targhee and Bridger-Teton National Forests, nestled between two grizzly bear-inhabited wilderness areas. It offers a rare blend of wild seclusion and approachable driving, making it a favorite for overlanders traveling between the parks.

The route is primarily well-graded gravel and is suitable for most vehicles with decent ground clearance. Four-wheel drive isn’t usually necessary in dry weather, but is strongly recommended during or after storms. Mud, erosion ruts, and slick spots are common in wet conditions and can catch less-prepared vehicles off guard.

Along the way, the road passes meadows, pine and aspen forests, and high-country lakes and streams, with Grassy Lake Reservoir serving as a scenic midpoint and a great location for dispersed camping. Wildlife sightings, including bears, moose, and deer, are common, and the remote feel of the area adds to the backcountry experience.

Camping is available in several forms. The eastern end of the road, within the John D. Rockefeller Jr. Memorial Parkway, includes eight designated dispersed camping areas with a total of 20 free, first-come, first-served sites. Each site includes a picnic table, bear box, and parking space. Each camp area also features a central vault toilet, trash receptacle, and recycling bins. Note that there is no water, electricity, or sewer service.

The best time to travel this road is summer through early fall. Snow often lingers into late spring and can return early at high elevations. The eastern end remains closed for grizzly bear migration until at least June 1st, though heavy snowpack may delay the opening further.