In addition to using K and W the US of course has been assigned the ITU prefixes of AA-AL and N. I wonder what would happen if they were would be used for broadcast usage. I imagine that ABC and NBC would use them to their advantage, but imagine some of the call signs we'd get...
ABCD-could have been used for the ABC station in Detroit instead of WXYZ

AARP
NUDE
NARC
NOOB
ABCD-could have been used for the ABC station in Detroit instead of WXYZ
AARP
NUDE
NARC
NOOB