Pompeys Pillar National Monument

On the expedition's return journey in 1806, the party split, and Clark led a group down the Yellowstone River. On July 25 he stopped at the butte, climbed it, and carved his name and the date into the soft sandstone, then noted the landmark in his journal. That inscription survived the centuries where the expedition's forts, caches, and camps did not, making it the one spot where you can stand exactly where a member of the Corps stood and see proof he was there.

Clark named the rock Pompy's Tower, after Pomp, the nickname he had given Jean Baptiste Charbonneau, Sacagawea's little boy. A later editor changed it to Pompeys Pillar, and the name stuck. The signature is now protected behind glass, and it was recognized when the site was named a National Historic Landmark in 1965 and a National Monument in 2001.

For thousands of years before Clark, Native peoples used this butte as a landmark for travel, hunting, and ceremony. It stood out on the open river plain, a natural waypoint on routes across the Yellowstone country, and the Apsaalooke, or Crow, whose homeland this is, knew it well and hold it in regard today.

The rock carries hundreds of markings beyond Clark's, including petroglyphs and pictographs left by those earlier peoples. Reading the butte, you can see it as a kind of guestbook of the plains, signed across many centuries by many hands.

A boardwalk and stairs climb the butte to a viewing platform at the summit. From the top, the Yellowstone River curls below through its cottonwood bottoms, and the high plains spread out toward distant ranges. It is easy to understand why a landmark this isolated drew travelers of every era.

The river bottom is good wildlife habitat, with deer, beaver, and a steady traffic of birds along the water, while raptors ride the thermals above the open butte. In summer the sandstone bakes and the cottonwoods offer welcome shade near the base.

The closest Boutel™ stays, so you can turn this stop into an overnight. Each is a place we chose through independent editorial review, never a paid placement.

Pompeys Pillar National Monument, near Billings in south-central Montana, protects a striking sandstone rock formation famous for bearing the carved signature of the explorer William Clark, the only remaining physical evidence along the Lewis and Clark expedition's route. As Clark traveled the Yellowstone River on the expedition's return in the early nineteenth century, he climbed the prominent rock and carved his name and the date into the sandstone, a signature that survives to this day, protected under glass. The rock, long a landmark used by Native peoples and bearing ancient petroglyphs as well, offers history, views, and a boardwalk to the signature. With its Clark signature and history, Pompeys Pillar National Monument offers a fascinating destination in Montana.

You can climb the boardwalk and stairs up the sandstone rock to see the carved signature of William Clark, protected under glass, view the ancient Native American petroglyphs and rock markings, take in sweeping views of the Yellowstone River valley from the top, and explore the interpretive center on the Lewis and Clark expedition and the site's history. The famous Clark signature, the ancient petroglyphs, the river views, and the interpretive center are the draws, offering a meaningful blend of exploration history and Native heritage. Seeing Clark's actual signature is remarkable. With its signature and history, Pompeys Pillar National Monument offers an engaging visit in Montana.

William Clark's signature at Pompeys Pillar is significant because it is considered the only remaining on-site physical evidence of the famous Lewis and Clark expedition along their entire route across the continent. As Clark traveled the Yellowstone River on the return journey, he carved his name and the date into the sandstone rock, and that signature survives, protected, to this day. The rock itself was long a landmark for Native peoples and bears ancient petroglyphs, layering its history. This tangible link to the expedition makes Pompeys Pillar a meaningful destination in Montana.

Pompeys Pillar is typically most accessible in the warm months of late spring through early fall, when the interpretive center and full facilities are open, so that season is best, with spring and fall offering pleasant weather and summer warm on the exposed rock, so mornings help then. Because facilities can be seasonal, checking current hours before you go is wise. For the fullest access and pleasant weather, aim for late spring through early fall at Pompeys Pillar National Monument in Montana.

Pompeys Pillar National Monument is near Billings in south-central Montana, along the Yellowstone River, within reach of Billings with the Moss Mansion and Pictograph Cave State Park, and south-central Montana. That makes Pompeys Pillar National Monument a fascinating stop to combine with Pictograph Cave State Park, the Moss Mansion, and the other attractions of the Billings area on a visit to Montana.