Since votes in USA are split fifty fifty among republicans and democrats ,
it could be fair to split the country into two as well,
to make everybody happy.
South USA and the North or
East and West this time.Then people could pack bags and move to the states they want to live in.Other model could even adopt federation of states like our Australia.
One contry, two presidents with states under each , mixed like swiss cheese.
For economy that new model may only benefit to all due to increased competition to fulfill people needs.From military point of view, will be less probable to involve in any military conflict when one side want the war and other is against.

Things will be a bit funny when Reds want to go on new war with Iran, since Blue promised to sell weapons to Iran to fight off invasion.
As for whole country is win win situation ,stimulating production and manufacturing sector.