After research, I tend to agree - though considering the much wider region. It looks like the 2 big dogs - NDSU and SDSU tap into the hidden gems across B1G country, forming a majority of their rosters from: Minn, Wisc, Ill, Iowa, Nebraska.
Montana St (not sure if they're the juggernaut NDSU is, but they seem consistently successful) otoh digs out of the Northwest - WA, OR, then also CA and TX
(oh and FL...all 3 recruit FL very well...a common theme)
Overall I was curious if there was something in the drinking water up there in the Dakotas or Montana - but it seems none of the 3 schools recruit the others' states - so I'm thinking not - but the theory seems correct regionally. There's enough good players in those well populated states surrounding them to pick up the best. I guess in the south they just go right to G5s or whatever since they're all seen.