Pompeys Pillar National Historic Landmark

28 Miles East of Billings, Montana | A Sandstone Storybook of the American West
 

On the banks of the Yellowstone River, a towering sandstone butte rises dramatically from the prairie. Known as Pompeys Pillar, this National Historic Landmark preserves the only remaining on-site physical evidence of the Lewis and Clark Expedition: Captain William Clark’s signature, carved into the rock on July 25, 1806.

As Clark and a portion of the Corps floated swiftly down the Yellowstone River, they paused to explore the massive rock formation. From its summit, Clark took in sweeping views of the surrounding lands—and left behind a legacy quite literally etched in stone.

"I marked my name and the day of the month and year." — Captain William Clark, July 25, 1806

He named the formation “Pompy’s Tower” in honor of Jean Baptiste Charbonneau, the infant son of Sacagawea and Toussaint Charbonneau. “Pompy” was Clark’s affectionate nickname for the boy, derived from a Shoshone word meaning “Little Chief” or “Leader.”

Clark’s Inscription & Other Rock Art

Clark’s carved name remains the site’s most famous feature, but it’s not alone. The sandstone pillar is a living record of the region’s rich cultural past, featuring:

• ✍️ Petroglyphs and pictographs created by Native peoples

• ✍️ Carved signatures from explorers, fur traders, and pioneers who followed

• 🪶 A sweeping view of the Yellowstone River Valley from the top of the pillar

Pompeys Pillar truly reads like a sandstone history book, offering visitors a rare, tangible connection to the westward expansion of the United States.

More About “Little Pomp” – Jean Baptiste Charbonneau

Born on February 11, 1805 at Fort Mandan in present-day North Dakota, Jean Baptiste Charbonneau was carried by Sacagawea on her back across the rugged terrain of the American West—beginning when he was just 54 days old. His birth was attended by Captain Lewis, who famously used rattlesnake tail in a remedy to ease labor.

Clark took a deep interest in the child’s future and later invited Sacagawea to bring Jean Baptiste to St. Louis, where he offered to raise and educate him. In 1809, she accepted. Jean Baptiste lived with Clark's family and grew up with access to the best education of the day.

A Life of Adventure

Jean Baptiste’s adult life mirrored the spirit of the expedition that marked his birth:

• Traveled to Europe with the Duke of Württemberg, learning German and assisting in scientific exploration

• Returned to St. Louis, worked as a fur trapper, guide, and interpreter

• Appointed judge and public administrator in California—but left after speaking out against mistreatment of Native people

• Joined the California Gold Rush, living near Sacramento for nearly 18 years

• At age 61, set out for Montana during another gold rush but died of pneumonia in Danner, Oregon, in 1866

Today, his grave has been restored and recognized as a historic site—fitting tribute to the boy born on the trail who lived a life of exploration.
 

📍 Plan Your Visit to Pompeys Pillar

Enjoy a scenic walk to the pillar, climb to Clark’s inscription, and explore the on-site visitor center and exhibits. Learn more about the Lewis and Clark Expedition, Sacagawea, and the enduring legacy of the child Clark called “Little Pomp.”

Pompeys Pillar has been preserved for you—and for future adventurers. As you explore this iconic site, take a moment to reflect on those who came before you and those who will follow in your footsteps.

🌐 Location: 28 miles east of Billings, Montana
🕰️ Open seasonally; check official site for hours
 

​