Approaching the crest of the Rockies on the Northern Pacific Railroad, the Lewis and Clark Cavern is passed fifty miles before reaching Butte. Its entrance is perched thirteen hundred feet above the broad valley of the Jefferson River, which the celebrated explorers followed on their westward journey; it overlooks fifty miles of their course.
The cavern, which has the usual characteristics of a limestone cave, slopes sharply back from its main entrance, following the dip of the strata. Some of its vaults are decorated in great splendor. The depredations of vandals were so damaging that in 1916 its entrance was closed by an iron gate.
This cavern is the only memorial of the Lewis and Clark expedition in the national parks system; there is no record that the explorers entered it or knew of its existence.
Two hundred and thirty miles east of the Cavern, Clark inscribed his name and the date, July 25, 1806, upon the face of a prominent butte known as Pompey’s Pillar. This would have been a far more appropriate monument to the most important of American explorations than the limestone cave. In fact, the Department of the Interior once attempted to have it proclaimed a national monument; the fact that it lay within an Indian allotment prevented. The entire course of this great expedition should be marked at significant points by appropriate national monuments.