http://www.businessinsider.com/a-marine-explains-which-state-would-win-if-the-us-declared-war-on-itself-2015-7
It would be interesting to me to see just what might happen if such things came about. Some enterprising wargamer could surely make a fun interesting what it?
Norm Koger’s “The Operational Art of War” is an option. There are several scenarios that take place from 1890’s, WWI, WWII, and 2000 something. Interesting that Harry Turtledove has produced books along the same timelines on the subject.