Airport Codes. If you’ve flown to Canada, you may have noticed that all major Canadian airports boast a code that starts with the letter ‘Y’.
‘Y’? You might ask? American airports look more this the city they are hosted in. So why do all Canadian airports start with ‘Y’? What’s with that?
Well first of all the International Air Transport Association (IATA) determines and deconflicts three-letter airport codes around the world. Back in the day, airports began receiving names. In the United States, they received three-letter codes that corresponded with their location or airport name: LAX (Los Angeles), MIA (Miami), BOS (Boston), CLT (Charlotte).
So back to Canada. Airport codes in Canada were apparently named after each region’s radio transmitter codes and vice versa. Canada had secured ‘Y’ for the beginning of its regional transmitter codes, and therefore kept it to refer to its airports as well.

Source: novaweather.net
Here are just a few. Note that regional airports don’t all follow the ‘Y’ theme, but the majority of the international terminals do.
YOW: Ottawa (McDonald-Cartier International)
YYZ: Toronto (Pearson International)
YVR: Vancouver International
YEG: Edmonton International
YHZ: Halifax International
YXE: Saskatoon (John G. Diefenbaker International)