This is a really interesting way of grouping the States. It's pretty clear that most of us forget that "state" is another term for "country" and that the name, "The United States of America" was at one time to make that clear. When abroad, I have often talked to people who had traveled to the States and had marveled at how different the real country is from their prior conceptions, which seem to be based on depictions of the East Coast, Texas, The South and the West Coast, only. Even for me, sometimes when I say "in America" I might really mean, "on the East Coast" because that's the America that I grew up in and began to understand the world through, which is of course a highly biased and regional view, the likes of which I suspect many slip into unconsciously.