Westward expansion in the United States following the Civil War was driven by several factors, including opportunities for land ownership enabled by laws like the Homestead Act, technological developments such as the Transcontinental Railroad, and the prospect of wealth from gold and silver discoveries. This movement significantly impacted indigenous peoples, forcing many from their traditional lands onto reservations through broken treaties and military conflicts like the Battle of the Little Bighorn. American Indian populations declined as a result of warfare, disease, and assimilation policies that sought to change their way of life.