Southwest Airlines is a major domestic airline that provides primarily short-haul, high-frequency, point-to-point, low-fare service. Southwest was incorporated in Texas and commenced customer service in 1971 with three Boeing 737 aircraft serving three Texas cities - Dallas, Houston and San Antonio. Today, Southwest operates more than 400 Boeing 737 aircraft in 60 cities and has more than 3,000 flights a day. The airline has the lowest operating cost structure in the domestic airline industry and consistently offers the lowest and simplest fares. It also has among the best overall customer service records. Southwest Airlines currently operates six reservations centers located in Albuquerque, N.M., Chicago, Houston, Oklahoma City, Phoenix, and San Antonio. The company trades on the New York Stock Exchange under the symbol LUV.