Pompeys Pillar: The Only Handwriting the Expedition Left

Every camp the Corps of Discovery made on this stretch of the Yellowstone, every cairn they stacked, every notch they cut into a tree, is gone. Two hundred twenty years of weather, river flooding, and two centuries of human activity have erased every physical trace of the thirty-three-member expedition except for one.

On July twenty-fifth, eighteen oh six, on the return leg of the journey, William Clark climbed a sandstone butte rising a hundred and fifty feet above the south bank of the Yellowstone River and carved his name and the date into the rock face. He called it Pompy's Tower, after Sacagawea's infant son Jean Baptiste Charbonneau, whom Clark had nicknamed Pompy and grown fond of over two years of travel. The carving is still there. A glass panel, installed in nineteen ninety-one, protects it from further weathering.

Clark's signature is not a monument or a plaque added later. It is the man's actual handwriting, made with a tool on a rock, on a specific day in the summer of eighteen oh six. It is the only physical inscription left by any member of the Corps of Discovery that survives on the American landscape. The Lewis and Clark Trail Heritage Foundation, which maintains the historical record for the expedition, is unequivocal about this. Everything else is gone.

The Pompeys Pillar National Monument is about twenty-five miles east of Billings. The glass-covered inscription is visible from the walkway. You are looking at someone's actual signature, not a replica, not a copy. The original.