United Airlines

United Airlines, Inc. is a major airline in the United States headquartered at 233 South Wacker Drive in the Willis Tower in Chicago, Illinois. United operates an extensive domestic and international route network across the United States and all six inhabited continents primarily out of its seven hubs, with Chicago–O'Hare having the largest number of daily flights and Denver carrying the most passengers in 2023. Regional service is operated by independent carriers under the brand name United Express.