But in the nineteenth century, they developed the Postal Service and it interacted with the railroad.

不过在19世纪人们发展出了邮政服务，人们发展出了邮政服务,并开始借助于火车。

耶鲁公开课 - 金融市场课程节选

They started having mail cars on trains and they started having postal sorting on the train.

人们开始用铁路邮政车,并且在火车上分类整理。

耶鲁公开课 - 金融市场课程节选