Originally Posted by
MrTickle
the 4 letter radio code thing is very strange, isn't it? must be a uniquely American thing
It's North American.
Canada and Mexico do it, too.
In the US west of the Mississippi, the station starts with K.
In the US east of the Mississippi, the station starts with W.
In Canada, the station starts with C.
In Mexico, the station starts with X.
There are some stations broadcasting out of northern Mexico with the intended audience of the US market, and are owned by US companies. This is because Mexico didn't have the same power restrictions, and there are some grandfathered Mexican stations with a super-strong signal. These are called "clear channel" stations, where their range is so wide that no other market in a large radius is allowed to have the same frequency.