This has so much potential. Hundreds of different factions scrambling for power. I think a lot of these would be unique to each state. Some of the larger factions would obviously be the U.S. Armed Forces, but who do they follow, and would they fight each other. The 9th and 10th Cavalry would be an excellent example, would they revolt if the Army follows a pro-fascist course. The CCC, Labor Unions, communists, anarchists, the KKK, Silver Shirts, and other fascists. Heck, the American Legion, Cox's Army, Oddfellows, Masons, Daughters of the American Revolution even. Henry Ford could be a supporter of the Fascists, easily producing vehicles, weapons, and sending forces out across America via his small private air force of ford tri-motors to stir up trouble, secure strategic resources, and help out in trouble spots. Why not even have Adolf send over some military advisers to help old Henry out. German subs in the Great Lakes, Italo Balbo and his flying boats doing commando style raids on the east coast. The Japanese using the occasion to move in on some U.S. territory, Hawaii, the Philippines, maybe even the Panama Canal. Why not have MacArthur making a deal with the Japanese (oh the irony) to help secure an unruly west coast, while he deals with the east, all in exchange for some much needed oil to run the Japanese war machine. French Foreign Legion, and the French Expeditionary force landing in New Orleans (where else). The roads are still in poor shape, and not likely to get fixed anytime soon, lots of horse cavalry put back into action. Fighting over the Texas-Oklahoma oil fields, West Virginia coal mines, and various industrial centers. The fledgling civilian aircraft business converted to war production, by putting guns on existing civilian planes. The 99's flying combat missions and air support (some air combat would be an interesting side on occasion).
sorry, just brain storming.
Lots of cool things that could be done with this setting.