But there was also a dark side to the historic national project. The railroad was completed by the sweat and muscle of exploited labor, it wiped out populations of buffalo, which had been essential to Indigenous communities, and it extended over land that had been unlawfully seized from tribal nations.

While the railroad revolutionized global commerce, it brought several significant negative consequences. Environmentally, the rapid expansion led to massive deforestation and the destruction of natural landscapes, while the noise and smoke from coal-burning locomotives caused early forms of industrial pollution. Socially, the railroad was a primary driver in the displacement of Indigenous populations, as tracks often cut through ancestral lands and facilitated the near-extinction of the American Bison, a vital resource for Plains tribes. The industry also concentrated immense wealth and power in the hands of "Robber Barons," leading to exploitative labor practices and corporate monopolies that stifled smaller businesses. In cities, rail yards and depots often divided neighborhoods, creating "wrong side of the tracks" socioeconomic barriers and exposing low-income residents to higher levels of noise and airborne pollutants. Furthermore, early rail travel was dangerous, with frequent accidents and boiler explosions causing high rates of injury and death among both workers and passengers.