"at" at end of sentence

[Douglas G. Wilson]

This final "at" was perfectly ordinary in Detroit during my childhood. I
can hardly believe that our cousins across the river in Windsor ON were
completely uncontaminated. It is my impression that the final "at" adds
useful redundancy in some cases. If I'm not paying attention, "Where IS
it?" sounds about like "What IS it?" etc., but "Where's it AT?" is clear
enough. "Where is it?" however has been OK everywhere I've been (I think);
is anybody suggesting that in some region the "at" is nearly obligatory?

-- Doug Wilson