Early Oregon Trail emigrants crested the south flank of Flagstaff Hill and, with the Blue Mountains looming to the west, saw a solitary tree in the valley below. Called l’arbre seul (the lone tree) by French-Canadian fur trappers, this large tree, possibly ponderosa pine or Douglas-fir, towered majestically above the floor of Baker Valley about three miles northwest of this marker. For many years--perhaps centuries--the Lone Tree served as a landmark for Indians, trappers, missionaries, and Oregon Trail emigrants, until felled in 1843 by what explorer John Fremont called, “some inconsiderate emigrant axe.”