United Air Lines, Inc., operating as United 
Airlines, is a major U.S. airline and is also the world’s largest airline by number of destinations and scheduled passenger-kilometer flown. It is a subsidiary of United Continental Holdings, with corporate headquarters in Chicago. United’s largest hub is George Bush Intercontinental Airport in Houston. United is a founding member of the Star Alliance, the largest airline alliance in the world. The airline’s regional service is United Express.
United was founded in 1926 as Varney Air Lines, becoming Boeing Air Transport in 1927 when it was purchased by aircraft manufacturer Boeing. United became an independent company in 1934 and merged with Capital Airlines in 1961. In 2011, United merged with Continental Airlines, replacing its own tulip logo with Continental’s globe logo as well as their aircraft livery.
Source: Wikipedia
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