The Takelma tribe of Native Americans originally called the rock "Tan-ts'at-seniphtha" (stone standing up), but to early settlers Pilot Rock was known as Boundary Mountain. The United States Exploring Expedition passed through the area on September 28, 1841, renaming the rock Emmons Peak after Lieutenant George F. Emmons, a U.S. naval officer and member of the group. Emmons described the rock as "a singular, isolated rock, which stands like a tower on the top of the ridge, rising above the surrounding forest with a bare and apparently unbroken surface." James Clyman also described the rock when he passed through the area on June 26, 1845. The rock later become known as Pilot Rock because it served as a landmark for pioneers coming north from California on the Applegate Trail, being visible from as far as the southern end of the Shasta Valley, over to the south.