Wow. That's the best explanation of the Fallout cultural timeline ever.
I think I'll just quote that whenever I see someone wanting rap in Fallout.

Thanks.

I believe the key point of divergence would have been President Truman failing to fire General McArthur like what happened in our timeline. McArthur would have gone ahead with his plans to use nukes in Korea, and America would not have been brought to a stalemate. One of the chief causes of the counter culture revolutions in our universe was, I believe, the failure of America in much of its operations overseas and around the world. The ongoing wars with no end and then no victory created a disillusionment with the government that undermined the propaganda and conservative line the public had been fed during the 1940s and 1950s.

MacArthur never had authority to use atomic weapons...only the President had that authority. MacArthur was fired because he was spoiled by the 12 year Administration of his cousin FDR and forgot his place. Of course, if Truman hadn't left South Korea out of the policy document that defined the US "Sphere of Interest" the North might not have felt they could safely atttack. I find it fascinating you and others appear to believe that the Korean War was "US warmongering" considering it was the North Koreans who attacked South Korea without provocation.....are you saying we should have left South Korea to Kim Jong-IL and his "Progressive" Police State?

Louis Prima is going to be essential if they're going for a 50s Vegas feel.

http://www.youtube.com/watch?v=YXYRkp2HZto
http://www.youtube.com/watch?v=LmlI0PD3gg0
http://www.youtube.com/watch?v=q4V8pbg3rNU
http://www.youtube.com/watch?v=PIJzpdJIdmI

I think it is safe to say that metal, grunge, disco, electronica, etc. never happened in Fallout's universe. This is because the whole reason given for the divergence from our own timeline is that the social revolutions of the late 1950s and 1960s and 1970s never happened in the Fallout universe. There was never a counter-culture movement. Everyone toed the line and supported the Americana ideal of a house with a white picket fence, a working father, a stay-at-home housewife, and 2 kids and a dog. There was never a backlash like what happened in our own timeline. Patriotism stayed high, the kids ate their vegetables and became good citizens rather than pressing back by becoming hippies. The Women's Rights movement of the 1970s never happened.

America continued going to war in places like Korea and Vietnam to battle the "communist" threat, but never lost like in our timeline, because General McArthur likely had his way and started the precedent of using nuclear weapons in conventional warfare. The widespread use and acceptance of nuclear weapons led to accelerated research and development in the nuclear fields, resulting in the advanced development of smaller and more stable fusion generators. The oil and gas shortages still occurred like in our own timeline, but rather than be forced to look for alternative energy sources, upon which research had never started (unlike the green movement in our timeline), in Fallout's universe, they had the ready solution at hand - the fusion generators. America became an near unrivaled super power, because we now controlled the power source to run much of the worlds technology, exporting fusion generators and using them to run our war machine.

China was the only one that could possibly resist, due to their large population. Eventually due to lack of resources, and because war had never failed this America before (thus keeping the patriotic fervor in the country at a fever pitch), America invaded and annexed Canada, which has one of the largest deposits of high-grade uranium in the world. America needed the land for its people, and the uranium to fuel our bombs, machines, and super soldiers for the inevitable expansion of our empire. Enough to pose a now legitimate threat to China, probably the last stronghold of Communism left in Fallout universe. No one knows what happened next, but the world was nuked. Could have been America. Could have been China. Could have been both.

There is even an argument that the Elvis in Fallout's universe is not quite the same as in our own. It is likely Elvis became popular for his gospel music, light pop songs, etc. and never wrote or recorded any of his more controversial (for their time) songs like happened in our own universe. Who knows? Maybe Elvis never even became addicted to drugs and overdosed in the Fallout universe.

Anyway, all this is to say I don't think there is a chance in hell that metal or grunge or anything not easily digestible by the very conservative middle class American family ever happened in the Fallout universe.

while I like your reasoning, its a bit off. Check out the fallout bible, the first couple parts anyway. it has a great timeline that shows how it all went down. for example fusion power didnt arrive til very late in "Fallout history", right before the nukes went off actually and Mac never nuked anybody in the fallout time line. A nuke did go off in Tel Aviv I think, a fuel war between Europe and the Middle east started that chain of events.

So Lock this topic plz