Fort Union was established in 1851 by Colonel Edwin V. Sumner in the Wolf Creek Valley of New Mexico. It was an important point on the Santa Fe Trail until 1879, when the coming of the railroad changed the trading patterns that had started with the trail in 1821. Evidence of the past, in the form of crumblings [sic] walls and eroding ruts cut by wagons traversing the prairies, may be seen at Fort Union National monument. Visitors may note that six miles to the south, the Mountain Branch of the Santa Fe Trail joined the Cimarron Branch, the ruts still visible from the entrance road to the monument. The author of this study, Robert M. Utley, first researched Fort Union while he was with the National Park Service. He revised and updated his earlier material on the historic site for this study. Since retiring from the Park Service in 1980, he has devoted his time to writing. Two of his nonfiction works, an account of the Lincoln County War in New Mexico and a biography of Custer, won back-to-back Western Heritage awards from the National Cowboy Hall of Fame in 1988 and 1989 -- Back cover.