Of course. But you've just divided the US into more than 4 quadrants by using the phrase mid-west
If there is northwest, southwest, northeast, and southeast ... that's 4 right there
So I believe the country is much more complex than a mere 4 quadrants ...
That said, of course there are going to be different lines by region. Since Patrick was a major breeder in the southwest, there were a lot of Patrick dogs out here. I would say Carver-type dogs are more prevalent in Texas, Tant and Boyles dogs in the south, etc.
The thing is, though, with this amazing invention we have called "the airplane," dogs can pretty much be sent all over the world, so some really major breeders, who've prolifically sent dogs all over the world for the last 2-3 decades, are going to have a much more global influence ... than some guy who doesn't do hardly any breeding and who keeps his dogs local.
Jack