WN is the IATA code for Southwest Airlines. Southwest Airlines is a major airline based in the United States and the worlds largest low-cost carrier. It is headquartered in Dallas, Texas, and has scheduled service to 121 destinations in the United States and 10 additional countries. Southwest Airlines operates 771 aircraft as of December 2022. The airlines first choice for its IATA code was SW, but it was already in use by Seabord World, a freight outfit. Another theory is that Southwest wanted to be snarky and flipped the "NW" in Northwest Airlines around to become "WN". However, the most likely explanation is that an African airline held claim to "SW" before Southwest came along, so Southwest had to pick something else.