The Great Fall by Air

The fruits of the captains’ inquiries in and around St. Louis during the winter of 1804 included copies of maps and journals made by a Welshman named John Evans while on a Spanish-sponsored expedition to find a Northwest Passage in 1795–97. Evans got no farther than the Knife River villages, but there he queried his Indian hosts about Western geography and learned of a waterfall “of an astonishing height” about six hundred miles west of the Mandans.

Lewis and Clark similarly mined the knowledge of the Mandans and Hidatsas while at Fort Mandan. They left with the information that confirmed an earlier report of “a most tremendious Cataract” many miles farther up the Missouri, and that “the nois it makes can be heard at a great distance.”

On 11 June 1805, Lewis proceeded ahead of Clark and the canoes, accompanied by George Drouillard and Pvts. Joseph Field, George Gibson, and Silas Goodrich. Shortly before noon on the thirteenth, Lewis’s ears “were saluted with the agreeable sound of a fall of water,” which “soon began to make a roaring too tremendious to be mistaken for any cause short of the great falls of the Missouri.” Probably somewhere to the right of the powerhouse in the photo, he then “hurryed down the hill which was about 200 feet high and difficult of access, to gaze on this sublimely grand specticle.”

Lewis wrote a detailed description of “this majestically grand scenery,” and even sketched “some of the stronger features of this seen” (the sketch has never been found), in hope that he could “give to the world some faint idea of an object which at this moment fills me with such pleasure and astonishment.”^[1]See also Lewis at the Great Fall.

Ryan Dam, shown here, was completed in 1915, and still impounds a small reservoir. The penstock and powerhouse at right displaced about one-third of the original width of the cataract. In early spring, the orderly overflow at the spillway dwarfs all that remains of the sight that thrilled Meriwether Lewis.