The Boeing 737 program has been one of the most successful narrowbody aircraft families for the US manufacturer. It was initially designed to replace the 727 and quickly became a workhorse for airlines worldwide, and has remained in continuous production for more than five decades. For United Airlines, the 737 has long been a key part of its fleet strategy. The carrier was the launch customer for the 737-200 and continues to be one of the largest operators of the type globally.

Over the decades, it has flown several variants of the aircraft, including the latest MAX models. Today, roughly half of United’s fleet consists of 737s. According to ch-aviation data, the airline currently operates 40 Boeing 737-700s, 123 737 MAX 8s, 141 737-800s, 113 737 MAX 9s, 12 737-900s, and 136 737-900ERs. It also has 110 additional 737 MAX 9s on order.

Where United Deploys Its Boeing 737 MAX 8

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United Airlines is the second-largest operator of the Boeing 737 MAX family. The Star Alliance member received its first 737 MAX (MAX 9) in April 2018 and has steadily expanded its fleet since. The smaller MAX 8 variant joined its fleet in 2024 and has quickly become an important part of its short- and medium-haul operations. According to data from aviation analytics provider Cirium, United has scheduled more than 145,000 flights with the 737 MAX 8 for 2025.

In November alone, the type is expected to operate over 12,000 flights. Unsurprisingly, the aircraft is primarily used on domestic routes such as New York LaGuardia–Denver, Newark–Boston, Denver–San Diego, and Newark–Miami. That being said, it also serves several international destinations across Latin America and Canada, including Guatemala City, Bogota, Mexico City, Calgary, and Vancouver.

Interestingly, United also deploys the MAX 8 on a couple of transatlantic routes from its Newark hub, including its newly launched service to Funchal and Ponta Delgada. Looking ahead to summer 2026, the carrier plans to expand its MAX 8 network further with the return of Newark–Glasgow service and the launch of a new route to Santiago de Compostela.

Over 111,000 Flights: Where United Airlines Deploys The MAX 9

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Furthermore, United Airlines is the largest operator of the Boeing 737 MAX 9. As mentioned earlier, the airline currently flies more than 100 of the type and has another 110 on order. Indeed, the MAX 9 has become a key part of the carrier’s narrowbody strategy and will eventually become the most common variant in its fleet once deliveries are complete. However, many of you would know this wasn’t always the case. United had initially ordered the larger 737 MAX 10, but certification delays prompted it to revise its fleet plans.

The first MAX 10 deliveries were once expected in 2020, but ongoing regulatory hurdles have repeatedly delayed the program. Therefore, in January 2024, United formally removed the MAX 10 from its internal fleet plan. The airline converted 100 of those orders to the MAX 9 and later added more aircraft to meet demand. According to Cirium data, the Chicago-based carrier scheduled more than 111,000 flights using the 737 MAX 9 this year.

The type is primarily used on domestic routes, including Los Angeles–Houston, Washington Dulles–San Francisco, Boston–San Francisco, and Raleigh–Chicago O’Hare. It also operates on select short international services such as Houston–Cancun and Newark–Cancun. In November, the airline will operate around 10,000 MAX 9 flights, with the highest frequencies on routes like Los Angeles–Houston, Houston–San Francisco, Raleigh–Chicago, and Washington Dulles–San Francisco, all of which see up to five daily departures in each direction.

Newark, Houston & San Francisco Lead United’s MAX Operations

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Indeed, the Boeing 737 family has become central to United Airlines’ operations. Before completing its merger with Continental Airlines in 2012, the carrier relied heavily on the Airbus A319, A320, and Boeing 757-200 for short- and medium-haul services. After the merger, however, it inherited a large 737 fleet from Continental and started to phase out older narrowbody fleets. In the years that followed, the Star Alliance member placed additional orders for the 737 family and committed to a significant number of 737 MAX aircraft, which now serve as the backbone of its domestic and some of its international networks.

The MAX aircraft are now spread across United’s major hubs; some bases are seeing particularly high departures. According to Cirium data for November, the 737 MAX 8 is most active at Newark Liberty, San Francisco, and Houston Intercontinental. From Newark alone, it will operate up to 65 daily flights, while San Francisco will see around 50 and Houston around 35 to 36 daily departures.

Similarly, the MAX 9 is concentrated at Newark, Houston, and San Francisco, where the airline has scheduled more than 10,000 flights for 2025. In November, Newark and Houston will again be the busiest hubs, with the MAX 9 operating roughly 1,285 flights from Newark (up to 45 daily) and 1,116 from Houston (up to 40 daily). Notably, the busiest destination from Houston will be Cancún, with up to four daily flights. Besides, other key MAX bases include Denver, Washington Dulles, and Chicago O’Hare.