Southwest Airlines is a low-cost airline in the United States. It is headquartered in the Love Field neighborhood of Dallas, Texas. It is the fourth-largest airline in North America when measured by passengers carried, as of 2024. With its all-Boeing 737 fleet, Southwest serves over 100 destinations in 42 states, Washington, D.C., Puerto Rico, and ten other countries and territories near the southern United States in the Gulf of Mexico and Caribbean Sea regions: Aruba, the Bahamas, Belize, the Cayman Islands, Costa Rica, Cuba, the Dominican Republic, Mexico, Jamaica, and Turks and Caicos Islands. 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.