Southwest Airlines 

Southwest Airlines is the largest domestic air carrier in the United States by passengers boarded. Southwest operates nearly 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 with a simple cabin configuration in a point-to-point network. In early 2026, Southwest modified its cabins to offer some rows with extra legroom, its ticketing process and merchandising to offer assigned seats, and more fare categories to include a basic economy class that appears for the first time in travel aggregators' search results and more directly competes with other airlines' offerings.