On July 3, 1806, after crossing the Continental Divide, the Corps split into separate groups so Lewis could explore the Marias River. Lewis and Clark stayed separated until they reached the confluence of the Yellowstone and Missouri Rivers. During their separation, Captain William Clark visited Pompeys Pillar on July 25, 1806.
On July 25, in Clark’s group, the nine floaters noticed a huge sandstone rock “200 feet high and 400 paces in circumference” not far from the river. Clark climbed it and saw “Emence herds of Buffalows, Elk and wolves.” Indian pictographs were on the rock, and to them he added his name and the date: Wm. Clark, July 25, 1806. He named the rock Pompy’s Tower (now called Pompeys Pillar) after Sacagawea’s baby, whom she carried on a cradleboard strapped to her back for the 14 months that she accompanied and aided the expedition.
A boardwalk leads to Capt. Clark’s signature and to the top of the Pillar. Trails lead visitors past a replica of Captain Clark’s canoes and to a view of the 670 mile-long Yellowstone River. The Friends of Pompeys Pillar, in conjunction with the Bureau of Land Management, hosts “Clark Days” on a weekend near the date each year to commemorate Captain William Clark’s visit to the site.
The Pillar overlooks the Yellowstone River about 25 miles east of Billings, Montana. The area is easily accessible from Interstate 94, using exit 23, or from State Highway 312. The Pillar is a sandstone butte or mesa covering about 2 acres at its base and standing about 150 feet high. Because it is the only sandstone outcrop on the south side of the Yellowstone River for several miles in either direction, it has been a landmark for centuries.
$7.00 per vehicle per day
1-6 People $25.00
7-24 People $40.00
>25 People $100.00
Pompeys Pillar National Monument accepts the following interagency passes:
All of these passes (except Volunteer) are also available for sale on-site.
Open daily for drive-in 8 a.m. to 6 p.m. May through September
Visitors may walk-in 365 days a year from dawn to dusk. (Walk from front gate to the Pillar is approximately 1 mile.)
The Interpretive Center is open the first weekend in May and closes for the season the last Saturday in September which coincides with National Public Lands Day.
Pompeys Pillar National Monument Information Center: 406-875-2400
The concrete Riverwalk, representing the Yellowstone River, begins in the parking lot and meanders through the interpretative center to the base of the Pillar. Signs along the path quote from Clark’s journals and tell of the party’s experiences from their entry on the Yellowstone on July 15, 1806, to their encampment at the confluence of Yellowstone and Missouri Rivers on August 3.