Hmmmm...interesting.
In the early 70's I was interviewed by a headhunter who mentioned that the company liked to hire young men from the South. (and this for a national position that only required being close to a major airport).
Curious, I asked him "Why?".
He said, (in all seriousness) "Because we don't have to teach them manners".
Unfortunately this has probably changed.
(Not the need for manners...but the humble source)
I also heard that hiring people from the small and medium towns of the mid-west is a good bet.