Delta Air Lines, Inc. is a large airline from the United States. They are headquartered in Atlanta, Georgia. Their largest hub is also in Atlanta. Delta's first flight was in 1929. In 1972, Delta merged with Northeast Airlines. In 1987, Delta merged with Western Airlines. In 2009, they merged with Northwest Airlines. Until 2013, Delta was the world's largest airline. As of 2016, the airline goes to 334 cities and has 819 planes.