The document discusses the three main reasons why homesteaders moved to settle on the Great Plains in the late 19th century. The first reason was government acts, like the Homestead Act of 1862, which offered settlers free land in exchange for farming it for five years. The second reason was the aftermath of the Civil War, as ex-soldiers from both sides sought a fresh start. The third reason was the development of transcontinental railroads, which made travel to and commerce on the Plains easier while also selling land adjacent to the rail lines.