I heard a statistic the other day that only 9 of the top 100 HS football players are from the B1G footprint (not sure what that meant w/ Rutgers, Maryland). I recognize that this could be an anamoly, but converntional wisdom (whatever that means) seems to hold that this is a trend. The ramification for Michigan was that it is going to be increasingly important to import talent from other regions and that might make it increasingly difficult to compete.
Part of the explanation was "demographic" shift. But, I looked it up and the US Census reports that roughly 24% of those under 18 live in the "midwest". So while, there is a shift in population, it is not like the midwest has been totally vacated. In tennis, golf and baseball, the relatively nicer weather allows players to practice their sports more outside the midwest, but this would seem to be less of factor for football which is playable is worse weather and is relatively more dependent on weight room training than actual skill practice. There is always the chance for confirmation bias, but it does seem like relatively more talent comes out of other regions, especially the south.
So, that seems to leave cultural aspects to explain much of the gap. Is it just the increased cultural interest in youth football in places like Florida and Texas that drives this?