The service, developed as part of a nationwide "fast-mail" system, was inaugurated on March 13, 1884, with a special run departing northward from Chicago at 3:04 AM (four minutes late owing to a late arrival in Chicago by the connecting fast mail train from New York), arriving in Minneapolis at 3:50 PM the same day.

For the first run, the train carried dignitaries from the Railway Mail Service, the Milwaukee Road and a few express agencies.

In 1899, the Post Office Department put forth a plan to reduce the travel time across the country, so the Milwaukee added two more trains, reducing travel time for mail between New York and Washington states from 122 hours to 95 hours.

[18] All other Milwaukee Road trains were required to clear the line ahead of the Fast Mail's arrival so it could keep its high speed schedule.

[23] A coach was added to train 56 in 1915 with scheduled stops in West Salem, Bangor, and Sparta.

[14] The Fast Mail was discontinued with the advent of Amtrak,[25] and the final run of train 56 arrived in Chicago on May 1, 1971.

[26] On June 12, 1924, the Fast Mail was stopped and robbed by the Newton Gang at Rondout, Illinois, in what has been called the biggest train robbery in U.S.