Airport coding first started in the 1930s, and at that time, airlines typically chose their own two-letter codes. This was fine when air travel was limited and there were only a few airports.

The Airport Codes website provides stories behind more than 350 airport codes around the world. The following gallery offers a sampling, with back stories provided courtesy of the site.

The carriers are now codesharing on flights operated by both airlines between Dublin Airport (DUB) and Philadelphia International Airport (PHL). American has also added its code to Aer Lingus ...