The Lewis and Clark Expedition passed this way on its westward trek across the continent. Expedition members camped on the west side of the Missouri River on July 25, 1805, a short distance upstream from present day Toston Dam. Near this location on July 26, Captain Meriwether Lewis discovered and described Stipa comata, commonly known as Needle and Thread grass. Captain Clark also identified on a map the large spring that can still be seen today 0.5 mile below the dam. The rocky cliffs on either side of the river downstream from this location were significant landmarks that Indian informants at Fort Mandan in present day North Dakota had previously described to the expedition leaders as the "Little Gates of the Mountains," where the second chain of Rocky Mountains approached the river. The more notable "Gate of the Rocky Mountains" are located approximately 60 miles downstream.