The Missouri National Recreational River preserves two splendid segments of the free-flowing, once unpredictable "Big Muddy," natural-appearing reaches reminiscent of the river recorded in the journals of captains Lewis and Clark and four other members of the Corps of Discovery. Much has changed along the route since "Mr. Lewis' Tour" first passed through the middle Missouri region two centuries ago, as human and natural forces have altered or obliterated many historic and natural features seen by the expedition, yet a good amount remains suggestive of the 1804-06 landscape. Along this stretch of the middle Missouri River, associated sites range from the Sgt. Floyd Monument in Sioux City, Iowa, to views of the river, its sandbars, and snags from scenic overlooks, to "The Tower" (Old Baldy) near where the expedition first encountered prairie dogs.