Southwest Airlines Co. is commonly known as Southwest. It is the largest airline in America and is the most popular low-cost carrier.

Herb Kelleher, Rollin King, and the airline were founded on March 15, 1967, as Air Southwest Co. The airline changed its name to Southwest Airlines Co. in 1971 when it became an intrastate carrier wholly within Texas. In 1979, it started interstate service between Dallas, Houston and San Antonio. Over the next decades, the airline expanded nationwide.