United Airlines, Inc. is a major airline in the United States headquartered in Chicago, Illinois. It operates an extensive domestic and international route network across the United States and to destinations on six continents. Regional service is provided by independent carriers operating under the United Express brand, and the Star Alliance, of which United was one of the five founding airlines, extends its network throughout the world.
United traces its origins to the late 1920s through the merger of several early airlines, the oldest of which was Varney Air Lines, founded in 1926 by Walter Varney. Because Varney was incorporated into the company, United often cites 1926 as its founding year. United has remained one of the largest airlines in the world for much of its history, including through successive mergers and acquisitions.