Confluence of Missouri and Niobrara rivers  -  Niobrara State Park, NE.  Here the Corps met with the friendly Yankton Sioux, who warned them of the Teton Sioux upriver.  The Corps members saw their first "tipi" -- a very efficient home for the Indians who moved often in search of game.  They also saw their first prairie dog town, and called the animals "barking squirrels."
Photo:  ©Charley Van Pelt