An expressman (pl. expressmen) refers to anyone who has the duty of packing, managing, and ensuring the delivery of any cargo.
During the late 19th and early 20th centuries, an expressman was someone whose responsibility it was to ensure the safe delivery of gold or currency, being shipped by railroad, and which was secured in the "express car". This job included guarding the safe or other strongboxes or coffers against outlaws, and memorizing the safe's combination to use at delivery.