Los Angeles Airport United Airlines DC-4 Mainliner Airplane Real Photo Postcard

The Douglas DC-4, initially conceived as a military transport (C-54 Skymaster) during World War II, rapidly transitioned to civilian service post-war, becoming a cornerstone of commercial aviation. Its robust four-engine design provided unprecedented range and passenger capacity, allowing major carriers like United Air Lines to expand transcontinental routes. United branded these aircraft Mainliners, signifying their role on key routes and symbolizing the cutting edge of air travel in the immediate post-war period.