Southwest Airlines Co. (NYSE: LUV) is an American low-cost airline based in Dallas, Texas, with its largest focus city at Las Vegas' McCarran International Airport. It is the largest airline in the United States by number of passengers carried domestically per year(as of December 31, 2007). It is also the 6th largest U.S. airline by revenue. It also maintains the fifth-largest passenger fleet of aircraft among all of the world's commercial airlines. As of July 12, 2008, Southwest operates approximately 3,500 flights daily.

Southwest Airlines has carried more customers than any other U.S. airline since August 2006 for combined domestic and international passengers according to the U.S. Department of Transportation’s Bureau of Transportation Statistics. Southwest Airlines is one of the world's most profitable airlines, posting a profit for the 35th consecutive year in January 2008.