These slaves undertook long and often extremely dangerous journeys to escape from the southern states of America in attempts to gain their liberty in the north. the routes were highly secretive, and those who were involved in the system used special words based on the language of genuine railways to protect themselves. Slaves who escaped (escapees) were known as 'passengers', or 'cargo'.
こうした奴隷たちは、アメリカ南部の州から逃げ出して北部で自由を得ようと、長く、しばしば極めて危険な旅路を選んだ。道筋は極秘であり、こうした脱出体系に関わった者は、自分たちを守るために、本物の鉄道用語に由来する特別な言葉を使った。逃げ出した奴隷（脱走者）は、「乗客」「貨物」などと呼ばれた。
