But when you try to imagine how it could be split up there are all kinds of problems. e.g., obviously CA + NY makes sense plus some large cities(e.g., Chicago). It all seems untenable w/o excessive relocation a la Stalin.

Truly splitting up the USA would require a war and that's more trouble than its worth in most peoples' opinions: I've kinda grown fond of letting my neighbor's kid cut the lawn for $25, even though he is a Democrat.

Now, OTOH, spinning off a state or two is within reach: e.g., giving CA and NY their independence would be fine with me. But then that's just me!8-))