Splitting the US, whatever the borders you choose, would be messy. India/Pakistan/Bangladesh style maybe ? The divide in the US is mostly urban/rural (except in new england where the rural areas are sometimes democratic too) : while Tallahassee is in the middle of very red areas it is a rather left wing place. BTW that urban/rural divide is not only a US thing. Impoverished rural areas are voting for the far right in great numbers in europe as well.