Although United Airlines can trace its history back to Varney Air Lines, a mail carrier in Boise, Idaho founded in 1926, the United name didn’t come about until 1929.
This happened when William Boeing merged his Boeing Air Transport mail service with Pratt & Whitney, the aircraft engine maker, to form United Aircraft and Transport Corporation (UATC).
In 1931, UATC formed United Air Lines to combine all of its passenger and mail airline services under one legal entity.
The company was broken up in 1934 in the wake of Air Mail scandal, where the major airlines colluded with certain government officials to split the spoils of the government-awarded air mail contracts amongst themselves.
In a provision aimed at preventing airlines and airplane manufacturers from being owned by the same company, UATC was broken up into three parts: United Air Lines, which evolved into the airline company we know today; United Aircraft, which took all manufacturing assets east of the Mississippi and is now known as United Technologies; and Boeing Airplane Company, taking all the plants west of the Mississippi and is now one of the two largest airplane manufacturers in the world.