The following commentary comes from an independent investor or market observer as part of TheStreet's guest contributor program, which is separate from the company's news coverage.NEW YORK ( Insider Monkey) -- When it comes to domestic airlines, there are four main players in the U.S.: Delta Airlines ( DAL), US Airways ( LCC), United Continental ( UAL) and American Airlines, which filed for bankruptcy protection in November. However, if DAL has its way, that all could soon change. DAL, a member of the SkyTeam Alliance, is the world's largest airline by traffic when counting domestic and international travel according to the International Air Travel Authority. It transports just under 111.16 million passengers on domestic and international flights a year, 90.13 million of which are domestic. Delta has been studying US Airways ( LCC) as a possible acquisition target according to the Wall Street Journal. Follow TheStreet on Twitter and become a fan on Facebook. In comparison, LCC carries roughly 51.81 million passengers (domestic and international combined), 45.53 million of which are domestic. If the number of passengers carried stays the same, an acquisition of LCC could put DAL at 135.66 million domestic passengers a year, easily beating out domestic rival Southwest Airlines ( LUV) as the number one domestic carrier in the U.S. The deal would also push the number of Delta's passengers carried internationally to the sixth in the world, up from its current eighth-place ranking.