Originally Posted by
seacue
MSY (Moisant Field) is still the code for Louis Armstrong New Orleans International Airport.
In the US codes beginning with N were reserved at the start for the US Navy. Hence New Orleans (MSY), Nashville (BNA), Norfolk (ORF), etc for civilian airports. NYC is OK for the New York metro area, because that's not an airport.
K and W starters were also suppressed in the US, hence Kansas City (MKC) to avoid confusion with already established US radio station codes, which all start with K or W.