Tower Rock marked the end of the first phase of the Lewis and Clark Expedition and the beginning of the next--the transition from the familiarity of the Great Plains to the unknown terrain of the Rocky Mountains and the Pacific Northwest. Having just completed the Great Falls Portage the previous day, Lewis, Drouillard, John Potts and Jean Baptiste LePage set out on July 16, 1805, to explore the area where the Missouri River enters the Big Belt Canyon in the Adel range of the Rocky Mountains. Up to this point in their journey, they had been crossing territory that, though unexplored by Americans, was a familiar landscape--the animals, plants and rolling dry hills were similar to those they left in North Dakota.

In his journal Lewis noted the steep black "clifts" that bordered the Missouri River and the presence of an aboriginal trail on the west side of the river. He also was the first to describe Lone Pine Rapids (renamed Half-Breed Rapids). The group arrived at Tower Rock, which Lewis described as a:

Tower Rock from a distance Photo from National Register Collection, by Kristi Hager, Montana Historical Society

. . . a large rock of 400 feet high wich stands immediately in the gap which the missouri makes on it's passage from the mountains by a handsome little plain which surrounds it base on 3 sides and the Missouri washes it's base on the other, leaving it on the Lard. as it descends. this rock I called the tower. it may be ascended with some difficulty nearly to its summit, and from there is a most pleasing view of the country we are now about to leave. from it I saw this evening immense herds of buffaloe in the plains below. (Moulton 1987, 4: 387)

Until this point, while traveling through lands unexplored by Americans, the Corps of Discovery had some knowledge of the territory based on maps, descriptions and information gathered from Indians. Tower Rock marked the transition into the unfamiliar, as on either side of this landform, the explorers encountered a vastly different landscape.

Tower Rock is located on the west side of the Missouri River, approximately eight miles south of Cascade, Montana at Interstate 15 Interchange # 247.