United Airlines is one of the biggest airlines in the world, with a large domestic and international route network. Based in Chicago, Illinois, United flies to many different cities across the United States and all six inhabited continents. United has eight hubs, with Chicago–O'Hare being its largest in terms of passengers carried and the number of departures. It is a founding member of the Star Alliance, the world's largest airline alliance, with 28 member airlines. United Express is the brand name for regional service operated by independent carriers. The United brand name was established by the amalgamation of several airlines in the late 1920s, the oldest of which was Varney Air Lines, founded in 1926.