Wanderlust World Wanderlust World A common misconception places Yellowstone in Idaho. In reality, the world's first national park sits primarily in the northwest corner of Wyoming (about 96% of its 2.2 million acres). Small slivers extend into Montana (3%) to the north and Idaho (1%) to the west.
The Idaho portion—mostly the remote, less-visited southwestern corner—includes the headwaters of the Snake River and parts of the Caribou-Targhee National Forest. Many visitors enter from Idaho via US-20, leading to the association. But the iconic features—Old Faithful, Grand Prismatic Spring, the Grand Canyon of the Yellowstone, Yellowstone Lake—all lie in Wyoming.
If you're planning a trip, know that the five entrance stations are in three states: West Yellowstone and North Entrance (Gardiner) in Montana; Northeast Entrance (Cooke City) in Montana; East Entrance (Cody) and South Entrance (Jackson) in Wyoming. The Idaho boundary is unmarked by any major gateway.