Last and largest in the trio of successful US wartime transports, the Douglas C-54 Skymaster was a development of a civil airliner, the DC-4, which was not very successful on account of it being considered too large for its day. The C-54 had an excellent range as well as sturdy construction featuring a large freight doors and a strengthened floor. Usually flown from bases within the continental United States, the C-54 had sufficient range to transport troops and supplies to the various theaters of war where US forces were involved in, these included almost 80,000 crossings of the Atlantic: a testament to the C-54's reliability is the fact that out of all its ocean crossings during the war, only 3 aircraft were ever lost. The C-54 was also adapted as VIP transport, of which one was assigned to President Roosevelt equipped with a specially-made electric hoist for wheelchairs. After the war, the Skymaster became the main transport of the USAF and formed the backbone of the US contribution to the Berlin Airlift. Over 20 other countries eventually adopted the C-54 for both military and civil duties, with Britain being the only wartime operator.

The prototype DC-4 airliner first flew on 21 June 1938. After Pearl Harbor, 24 of these were converted into the initial C-54 followed later by the C-54A which were fitted with Twin Wasp radials. The C-54 was constantly improved: the C-54B had greater weights, integral wing tanks and could carry stretchers, the C-54D had uprated engines, the C-54E additional fuel capacity, and ultimately the definitive C-54G with Allison V-1710 engines. The C-54 also served in many other roles, these included a SC-54 SAR aircraft, the TC-54 trainer as well as reconnaissance (RC-54) and medical casevac (MC-54) versions. The VIP transport version was known as the C-54C.