well that's a novel approach. About tome someone though of that.
I read World War Three by ... damn I forget now. But the plot was that there had been a limited nuclear exchange between the US and Russia, but the Russian missiles had fallen short and basically landed on the East coast. The result was the fragmentation of the US into three fairly different countries (Southwest, Midwest and the North IIRC) and a technological regression of several decades had taken place so that for instance you could still buy one of the few cars they were making
but ... they were all Chevy Citations
(think of an American Austin Allegro)
It was fairly believable, at least in as much as history has shown us that when things look really bad, they're not quite as bad as they seem, or at least we eventually recover from them. Imagine describing our world to someone in 1944 for instance