An expressman refers to anyone who has the duty of packing, managing, and ensuring the delivery of any cargo

Cargo

Cargo is goods or produce transported, generally for commercial gain, by ship, aircraft, train, van or truck. In modern times, containers are used in most intermodal long-haul cargo transport.-Marine:...

 on board a train.

During the 19th century, an expressman was someone whose responsibility it was to ensure the safe delivery of a train

Train

A train is a connected series of vehicles for rail transport that move along a track to transport cargo or passengers from one place to another place. The track usually consists of two rails, but might also be a monorail or maglev guideway.Propulsion for the train is provided by a separate...

's gold

Gold

Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

 or currency

Currency

In economics, currency refers to a generally accepted medium of exchange. These are usually the coins and banknotes of a particular government, which comprise the physical aspects of a nation's money supply...

, which was secured in the "express car

Baggage car

A baggage car or luggage van is a type of railway vehicle often forming part of the composition of passenger trains and used to carry passengers' checked baggage, as well as parcels . Being typically coupled at the front of the train behind the locomotive, this type of car is sometimes described...

". This job included guarding the safe

Safe

A safe is a secure lockable box used for securing valuable objects against theft or damage. A safe is usually a hollow cuboid or cylinder, with one face removable or hinged to form a door. The body and door may be cast from metal or formed out of plastic through blow molding...

 or other strongboxes or coffers against outlaw

Outlaw

In historical legal systems, an outlaw is declared as outside the protection of the law. In pre-modern societies, this takes the burden of active prosecution of a criminal from the authorities. Instead, the criminal is withdrawn all legal protection, so that anyone is legally empowered to persecute...

s, and memorizing the safe's combination until delivery.

Expressmen make an appearance in Mark Twain

Mark Twain

Samuel Langhorne Clemens , better known by his pen name Mark Twain, was an American author and humorist...

's short tale, "The Invalid's Story."