When Meriwether Lewis and William Clark led the Corps of Discovery up the Missouri River, the mouth of the White Stone River, now known as the Vermillion River, lay near this site at Cotton Park. On August 24, 1804, nearly 50 men in two pirogues and a keelboat passed the confluence and camped on the Missouri southwest of the White Stone River's mouth. The next day, while the main party continued west, Lewis and Clark and a small group returned to the White Stone River, left their pirogue, and traveled overland to Spirit Mound, a place native peoples believed was occupied by powerful spirits. William Clark recorded crossing the creek, reaching the hill by midday, then returning by way of the creek and rejoining the pirogue at sunset before going on to the previous night's camp. The expedition passed the confluence again on its return journey on September 3, 1806. The Missouri continued to flow in a great bend beneath the bluff until spring 1881, when ice gorges broke upriver, blocked the downriver flow, destroyed old Vermillion, cut off the bend, and carved a new channel across the land south of here. Afterward, no longer a riverboat landing, Vermillion was rebuilt above the bluff, and the Vermillion River adopted part of the abandoned bend and lengthened its course to meet the Missouri. By 2004, the Vermillion River's mouth was about 3.5 miles southeast of the White Stone River's 1804 confluence with the Missouri near this site.