This is not really as well thought out and just something I did for fun, but at one point I decided to divide the contiguous 48 states (+DC) into 7 regions of 7 states each, and this is what I came up with:
amusing. equal number of states each, but try seven states with equal population each. That's harder. Here's a map with fifty states of equal population:
I think I live in Susquehana, which I would call part of the Middle Atlantic region. (It appears that Lancaster County is in Susquehana and neighboring Chester County is in Philadelphia, but I might be mistaken.)
In this map, I would define the midwest as Missouri, Lincoln, Green Bay, Wabash, Chicago, Michiana, Detroit, North Coast, Sohio, St. Croix, High Plains, Llano Estacado, and Brownia.
(I feel weird putting Sohio and North Coast in the "midwest" but no weirder than I feel putting Ohio, a state entirely within the easternmost of our four time zones, in the "midwest" and I always do, mostly because I've been told all my life that Ohio is in the Midwest.)