American manufacturers first produced toy trains in the early 1800s, in conjunction with the construction of the nation's railway system. Toy makers made the earliest toy trains from tin. After the American Civil War, manufacturers turned to sturdier cast iron for making toy trains. These cast-iron trains had axels and wheels or simple clockwork mechanisms that required manual propulsion. Their durability and realistic appearance made them an instant hit. Cast-iron trains remained in production until World War II, when manufacturers dedicated their time and materials to the war effort.