Southwest Airlines is one of the biggest airlines in the United States, and the largest low-cost airline in the world. Headquartered in Dallas, Texas, it now flies to more than 120 cities in the US, plus destinations in Mexico, Central America, and the Caribbean. Although Southwest Airlines stands out for its cheap and affordable fares, it is one of the only budget airlines in the US that offers complimentary food and drinks. It also offers more leg room than some of its closest rivals. Although it does not strictly offer first or business class tickets, travelers can be upgraded to bigger (and more comfortable) seats.