Yellowstone Falls consist of two major waterfalls on the Yellowstone River, within Yellowstone National Park, Wyoming, United States. As the Yellowstone river flows north from Yellowstone Lake, it leaves the Hayden Valley and plunges first over Upper Falls of the Yellowstone River and then a quarter mile (400 m) downstream over Lower Falls of the Yellowstone River, at which point it then enters the Grand Canyon of the Yellowstone, which is up to 1,000 feet (304 m) deep.
It is likely that Native American tribes knew of the falls for centuries. Captain William Clark of the Lewis and Clark Expedition made a note in his journal about hearing of the falls but did not believe the story. The first European to see the falls was likely French fur trapper Baptise Ducharme who claimed to see the falls in 1824, 1826 and 1839. Jim Bridger and fellow explorer James Gremmell claimed they visited the falls in 1846. In 1851, Bridger provided missionary Father Pierre-Jean De Smet a map showing the location of the falls. The Cook–Folsom–Peterson Expedition, a private group of three explorers named the falls in 1869. The earliest images of the falls were drawn by Private Charles Moore, a member of the U.S. Army escort of the Washburn-Langford-Doane Expedition which explored the Yellowstone River in August–September 1870. During the Hayden Expedition of 1871, the falls were documented in photographs by William Henry Jackson and later in paintings by Thomas Moran. In January 1887, Frank Jay Haynes took the first winter photographs of Lower Falls.
Over the years the estimates of the height of Lower Falls has varied dramatically. In 1851 Jim Bridger estimated its height at 250 feet. One outrageous newspaper story from 1867 placed its height at "thousands of feet". A map from 1869 gives the falls its current name of Lower Falls for the first time and estimates the height at 350 feet. However the current map lists Lower Falls at a height of 308 feet.