......1831 Treaty of Traverse des Sioux signed by the Indians, ceding to the United States the territory east of the Big Sioux River......1851 Gen. W. S. Harney, with 1,200 men, marches from the Platte River to Fort Pierre, where they encamp for the winter......1855 First settlement established at Sioux Falls by the Western Town-lot Company, of Dubuque, Ia......1857 By organizing Nebraska Terri...