Since a nuclear bomb isn't as devastating as most people think, (source: http://homepage.mac.com/msb/163x/faqs/nuclear_warfare_101.html, http://homepage.mac.com/msb/163x/faqs/nuclear_warfare_101.html and http://homepage.mac.com/msb/163x/faqs/nuclear_warfare_103.html), they need to throw a whole lot of them to be effective as a MAD-
Finally someone who realized this!
I think that since there wasn't a cold war nukes probally barely got passed a few megatons. I'd say though they would have had no limitation treaties, so the arsenals would have built and built and built. The US had about 32,000 at its peak in real life. Probally less than that, but maybe 20,000 in the Fallout world. They might have started to crank them out towards the end of the world ex. Fort Constantine with all its extra bombs.
Based on that I think China would have a bit more, as they were going to fall back on the plan so maybe 22,500.
There are about 19,000 cities in the US big and small. You destroy about 5,000 of those with bombs, and maybe throw some extras here and there. About 2 bombs per city, I'd say China has about 10,000 bombs left. They destroy warhouse with 1 each so minus about i don't know... 5,000. 3,000 are left to destroy military stuff, which should be easy enough, there aren't huge numbers of those. The last 2,000 go to other places.
Same with US, they are just more strategic and the soldiers made less land to nuke, so about 3,000 of their bombs go to other places.
Europe lauches say there whole combined total of 1,000 bombs. 250 to US 250 to China 500 to other countries
The rest of Asia, maybe 2,000 nukes. Again 250 to US 250 to China 1,500 to rest of the world.
Poissibility of USSR having a decent amoun maybe 3,000 500 to US 500 to China 2,000 to rest of the world
Alright as this is pure speculation, I think it turned out pretty well. The result would be definite destroyed world.
But, the point of me making this is to show how little the other countries probally got nuked compared to US and China. And we know that the west coast has at least 2 million citizens/people (including Caesar's Legion), well almost know.
Give the rest of the US 2 million as they had it worse. So US population 4-5 million. China probally would have 1-2 million total. And the rest of the world would outclass these countries with population.