United Airlines, Inc. is a major American airline headquartered at the Willis Tower in Chicago, Illinois. United operates a large domestic and international route network spanning cities large and small across the United States and all six inhabited continents. As of December 2022, the company had 92,795 employees. United Airlines is a member of the Star Alliance and has codeshare agreements with several airlines, including Air Canada, Air China, and All Nippon Airways. The United Club is the airline lounge associated with United Airlines and United Express carriers. United Polaris lounges are also available for international business class passengers.