What is en_US ?

[Bob Goodwin - W2BOD]

Timothy Murphy wrote:
> I know Americans spell a few words wrongly, but so what?
> Plenty of people make spelling mistakes,
> and it doesn't affect one's understanding in the slightest.
>   

    Wrongly?

    American English spellings are generally 20% more efficient when
    words such as "color" and "humor" are considered!  What point is
    there to throwing in extra letters other than to be different?  I
    suppose it creates jobs to maintain separate dictionaries and
    ensures that competition is minimized between publishes perhaps ...

    Bob Goodwin