Southwest Airlines began in 1967 with an idea sketched on a cocktail napkin. It officially incorporated on March 15, 1967 to provide air service between three Texas cities. Southwest faced legal challenges from established carriers but ultimately prevailed, helping deregulate the airline industry. Through strategies like the 10-minute turnaround and offering free liquor with tickets, Southwest established a low-cost leadership model. It has grown to be the largest carrier in the U.S. based on number of passengers by focusing on point-to-point routes, secondary airports, and differentiation through its culture and frequent flyer program.