National Train Day, the Saturday closest to May 10th. Trains revolutionized the world. Train routes hauled limestone, coal & other heavy materials long distances. Steam engines were instrumental in westward expansion in the United States, bringing settlers West & necessary supplies for them to start new lives. Trains have distinct categories separated by how the locomotives are powered, their use & design of the tracks. A train is a form of rail transport consisting of a series of “cars” run along a rail.