July 25 – On this day in Montana history in 1806 William Clark carved his name into the rock on Pompy’s Pillar on the Yellowstone River near what is now Billings. The inscription, “Wm Clark July 25 1806,” is the only permanent record left along the route of the Lewis and Clark Expedition. In his journal, Clark noted that the “Indians” had built two stone piles on the rock, which we now know is sacred to the Crow.