Quick Answer: 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. The principal figure behind the formation of the airline was William E. Boeing, founder of the Boeing Aircraft Company in 1916. He launched an air service between Victoria, British Columbia, and Seattle and later acquired three additional airlines, completing the merger by 1931 to form United Air Lines. Through successive mergers and acquisitions, United has remained one of the largest airlines in the world for much of its history.