This will kinda give you your answer.
https://www.midmajormadness.co...-teams-by-conference
But it seems they declare everything a midmajor that is not P5.
I think there is a low D1. I don't think I would consider Northeast, SWAC, Summit, MAAC, Ivy, Horizon, Big Sky, America East, and Meac mid maors. There are a few others that only fit there because of 2 or 3 teams. If you are not competing in end of season tournament consistently other than your guaranteed you are not a mid major conference. When you talk mid major teams, there are a lot of them.
I have heard some say you have teams that are mid major in one sport and not in another. Don't know if I agree with that.