Southwest Airlines is the largest domestic air carrier in the United States by passengers boarded. Southwest operates over 800 aircraft in an all-Boeing 737 fleet. Despite offering some longer routes and a few perks for business travelers, the airline predominantly specializes in short-haul, leisure flights operated in a single, open-seating cabin configuration in a point-to-point network. In 2025, Southwest will modify its cabins to offer some seats with extra legroom and will update its ticketing process to offer assigned seats.