 However, the railroad played a major role in sparking tensions with Native American tribes in the 1870s.Jay Cooke, the NPR president, launched major surveys into the Yellowstone valley in 1871, 1872, and 1873, which were challenged forcefully by the Sioux under chief Sitting Bull.These clashes, in part, contributed to the Panic of 1873, a financial crisis that delayed construction of the railroad into Montana.