United Airlines holds significant shares at major US airports

In March 2025, Cirium data shows United is scheduled to operate the most flights from Chicago O'Hare, with 32,562 flights and 4 million seats. Denver follows closely with 31,169 flights, but it carries slightly more seats (4,033,296) due to larger aircraft. Other major hubs include Houston, Newark, and San Francisco, with thousands of flights and millions of seats collectively.

At Newark Liberty, United holds a 67.4% market share, carrying 32.9 million passengers, including 24.2 million domestic and 8.7 million international travelers. Spirit Airlines, JetBlue, and American Airlines, among others, also operate at the airport but with significantly smaller shares. While United and JetBlue offer international flights from Newark, Spirit, American, Delta, and Alaska operate domestic services only.

The Federal Aviation Administration (FAA) has been focusing on increasing competition at Newark by redistributing slot permissions—take-off and landing permissions at congested airports. In late 2024, due to planned construction projects, the FAA relaxed slot requirements at Newark, impacting airport operations through 2026.

Across the airline industry, United's main competitors include American Airlines, Delta Air Lines, and Southwest Airlines, each with their own major hubs. American Airlines is most significant at Dallas/Fort Worth, Charlotte, and Miami, while Delta dominates Atlanta, Minneapolis, and Salt Lake City. Southwest Airlines' primary focus is domestic flights, holding a significant presence in Denver, Dallas, and Baltimore.

Overall, United Airlines continues to maintain its key positions across major U.S. airports, reflecting its substantial role in the industry.