An 1846 map by Augustus Mitchell “of Texas, Oregon and California, with regions adjoining.”

Augustus Mitchell’s map was the latest and most accurate map available to westward travelers in 1846. Brigham Young bought copies of Mitchell’s map to use in planning the Latter-day Saints’ departure and route. The Salt Lake Valley, located in a region the map called “Upper or New California,” was the Mormons’ intended destination, in part because of its geographic isolation. The starting point for the Mormon migration was Nauvoo, Illinois, on the western border of Illinois between Burlington, Iowa and St. Francisville, Missouri, just above the 40° latitude line on this map’s right-hand edge. Although Nauvoo is not noted on the map, it was located approximately where the “Mi” in “Mississippi River” is printed.