In Dawson County, much of the early history centered on the pioneer trails to the West. The Mormon Trail to Utah and the first transcontinental railroad passed along the north side of the Platte River, while the Oregon Trail and the Pony Express followed the south side. Conflict with Indians was not uncommon in the early days of settlement. In 1864, the Plum Creek Massacre occurred near here in Phelps County when Sioux Indians attacked a wagon train, killing several men and taking prisoners. In 1867, near here, a group of Cheyenne led by Chief Turkey Leg cut the telegraph line, derailed a locomotive, and killed several Union Pacific Railroad employees. The nearby town of Cozad lies directly on the 100th Meridian, an important goal in building the first transcontinental railroad. When the tracks reached this point in 1866, some 250 businessmen, senators, congressmen, and other notables came to celebrate. The 100th Meridian is often cited as the line of aridity, west of which rainfall is usually insufficient to support non-irrigated agriculture.