Grand Canyon of the Yellowstone

The Grand Canyon of the Yellowstone is the first large canyon on the Yellowstone River downstream from Yellowstone Falls in Yellowstone National Park. The canyon is approximately 24 miles long, between 800 feet and 1,200 feet deep and between one quarter of a mile and three quarters of a mile wide.

Although trappers and prospectors who visited the Yellowstone region had knowledge of the canyon, the first significant descriptions were publicized after the Cook–Folsom–Peterson Expedition of 1869 and the Washburn-Langford-Doane Expedition of 1870.