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Lewis and Clark
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Historic Sites and Buildings

Bureau of Land Management Pompey's Pillar [Pompy's Tower] National Monument

Location: Yellowstone County, on the south bank of the Yellowstone River, approximately one-half mile north of I-94 (U.S. 10), between the villages of Nibbe and Pompeys Pillar and some 28 miles northeast of Billings. Established as a National Monument on January 17, 2001; managed by the Bureau of Land Management (BLM).

William Clark's inscription of his name and the date on the northeastern face of this huge rock formation is the only surviving physical evidence known to remain along the route of the explorers that was left by them and can be indisputably associated with the expedition. Possibly two others in the party also etched their names, but this cannot be proven.

On the afternoon of July 25, 1806, while separated from the Lewis group on the return trip from the Pacific and proceeding down the Yellowstone River, Clark, York, Sacagawea, her infant son, Charbonneau, and four privates stopped at the river landmark. Some of them climbed it, and viewed the surrounding panorama of mountain plains and wildlife. Clark carved his name and the date near some Indian pictographs, which are not extant today. He apparently named the rock as "Pompy's Tower" after the infant, whom he called "Pomp" or "Little Pomp." But either Nicholas Biddle, the author, or Paul Allen, the editor, of a history of the expedition issued in 1814, renamed the rock as "Pompey's pillar."

After the stop there, the Clark party moved down to the Missouri. It reunited first, on August 8, with Sergeant Pryor and three men who had left the Clark group earlier and had been unable to complete a special mission; and later, on August 12, with the Lewis contingent.

Although Clark was the first white man to carve his name in the soft light sandstone of the massive formation, he was not the first to visit it. The year before, in September 1805, the Frenchman François Antoine Larocque paid a call while on a trapping expedition with some Crow Indians who had come to trade at the Mandan villages. Lewis and Clark had met him there during the winter of 1804-5.

Pompey's Pillar
Pompey;s Pillar. (Bureau of Land Management)

Subsequently, other explorers, trappers, soldiers, gold seekers, railroad surveyors, and steamboat crews passed or stopped at the well-known landmark. Many of them inscribed their calling cards. In 1876 Lt. James Bradley, chief of scouts for Col. John Gibbon's column in the campaign that climaxed in the Battle of the Little Bighorn, Mont., complained that one of his soldiers had carved his name across the "k" in Clark's name. Apparently he did not cut it deeply, however, for time has obscured the alteration.

In 1873 Lt. Col. George A. Custer camped near the rock with part of his 7th Cavalry while guarding a Northern Pacific survey party. A group of hostile Sioux fired on the cavalrymen from the opposite bank of the river. In later times, railroad passengers could readily see the landmark from train windows, as they still can today.

In the far distant geological past, the pillar was obviously part of the same formations now exposed in the bluffs a few hundred yards north across the river, but the stream eroded through a protruding headland and isolated the landmark that is seen today. As viewed from the west and south, the stone face of the pillar juts vertically above the level valley floor, more than a mile across at this point, sparsely populated and in agricultural use. The northeastern, or river, side of the rock gradually slopes downward to ground level. Contrary to most written descriptions, the overall height of the pillar, including its cap of earth, is probably not more than 120 feet above its base. The diameter of the long axis, running east to west, is about 350 feet. A strip of land 300 feet wide separates the rock from the riverbank.

The Clark etching, in script, reads as follows:

Wm Clark
July 25 1806
Clark's inscription on Pompey's Pillar
Clark's inscription on Pompeys Pillar, protected by shatterproof glass and a bronze frame. (National Park Service (Thomas K. Garry, 1965).)

Clark's inscription on
Pompey's Pillar
William Clark's signature, dated July 25, 1806. (Bureau of Land Management.)

Along with various other inscriptions, it is located on the eastern face on an overhanging wall of rock just below the top. The wall is about 7 feet above a short path running along the wall's base. The site is easily reached from one of several trails leading up the sloping northeastern face.

The Northern Pacific Railroad deserves major credit for preservation of the inscription. In 1882, when the line was building up the Yellowstone Valley, its officials noted that vandalism was rapidly effacing the etching and they installed over it a heavy double iron screen, or grating. Without this action, it likely would have been destroyed. The screen, however, did not impede weathering and erosion. It also made the inscription difficult to read and impossible to photograph effectively. On a visit in 1900, historian Olin D. Wheeler found that it had been scratched over and that various names had been cut all around it and just over and below some of the letters of Clark's name. All this had apparently been done before the screen was put in place. In 1926, responding to the interest of the Daughters of the American Revolution in deepening and freshening the inscription, the Northern Pacific hired a Billings marble and granite firm to deepen it.

In 1956, the year after a new private owner acquired the rock and surrounding land to preserve it as a historic monument, the iron grating was replaced with a heavy bullet and shatter-proof glass, edged in bronze. This left the inscription fully visible but protected it from the elements. Other steps later taken to enhance the area were the construction of a road from the highway, the grading of trails up the pillar, and installation of some steps and railings, as well as interpretive markers. In 1975, the site was owned by the widow of the 1955 purchaser and was open to the public at nominal cost. In 2001, it was declared a National Monument under the management of the Bureau of Land Management.

Last Updated: 22-Feb-2004