It was during the Age of the Iron Horse that delivery really started to pick up, in fact, the United States transported most bulk mail by train for nearly 100 years.

还是在铁马的时代期间，邮递才真正开始发展，事实上，美国通过火车运输大部分的大宗邮件将近100年。The first airmail service didn't start until 1918。第一次航空邮件服务（没有开始）直到1918年才开始。