As the Expedition moved into the area of current day Dillon, Sacagawea recognized a familiar rock formation. The captains thought this was a good sign in their search for the elusive Northwest Passage. Sacagawea's tribe, the Shoshone, called the landmark "Beaver's Head" because the natural formation resembled the head of a swimming beaver. Lewis entered in his journal, "the Indian woman recognized the point of a high plain to our right which she informed us was not very distant from the summer retreat of her nation on a river beyond the mountains which runs to the west. This hill she says her nation calls the beaver's head from a conceived re[se]mblance of it's figure to the head of that animal. She assures us that we shall either find her people on this river or on the river immediately west of its source…"
Three days later Lewis spotted a lone man, "with my glass I discovered from his dress that he was of a different nation from any that we had yet seen, and was satisfied of his being a Sosone [Shoshone]… I was overjoyed at the sight of this stranger and had no doubt of obtaining a friendly introduction to his nation provided I could get near enough to convince him of our being whitemen."
Lewis repeatedly tried to connect with the Indian, but the man rode off in haste. Lewis and two others tracked the man, knowing that the rest of the tribe could not be far off. Within two days they located the Shoshone camp and proceeded to trade with the tribe.
Beaverhead Rock became a state park in 1975 and the rock formation is listed on the National Register of Historic Places. Attractions near Beaverhead Rock include Clark's Lookout State Park, Bannack State Park, the Beaverhead County Museum in Dillon, and historic Virginia and Nevada cities.
