In ‘Folsom Prison Blues,’ Johnny Cash sings, “I hear that whistle blowin’/ I hang my head and cry.” The lyric is jarring because trains are about the freedom to travel, not imprisonment.

Trains propelled human beings into the modern world. Before trains, no human being had ever traveled faster than a horse. They have been integral to the growth of our economy, connecting societies, and providing the comforts we now enjoy. They are big and powerful, they are romantic – they represent freedom. However, when Johnny Cash sings about trains, he’s reminding Folsom Prison inmates about life passing them by because of their lost freedom.