Southwest Airlines Co. is a major airline in the United States that operates on a low-cost carrier model. It is headquartered in Love Field, Dallas, in the Dallas–Fort Worth metroplex, and has scheduled service to 121 destinations in the United States and ten other countries. As of 2018, Southwest carried more domestic passengers than any other United States airline. It is currently the third largest airline in the world based on passengers flown. The airline was established on March 9, 1967, by Herb Kelleher and Rollin King as Air Southwest Co. and adopted its current name, Southwest Airlines Co., in 1971, when it began operating as an intrastate airline wholly within the state of Texas, first flying between Dallas, Houston, and San Antonio. It began regional interstate service in 1979, expanding nationwide in the following decades. Southwest currently serves airports in 42 states and multiple Central American destinations. Southwest's business model is distinct from other US airlines as it uses a rolling hub and point-to-point network and allows free checked baggage. It exclusively uses Boeing 737 jets in its fleet. Wikipedia