USA came out as a victor in WW2, amongst many other allied countries, that is obvious, but to say they are the main reason why WW2 was won by the Allies is a complete crock of shit. Even when the USA and Britain dropped over 150,000 bombs via air raids on 6-7 German cities (including the complete destruction of Hamburg) the Nazis did not surrender. It's when the Red Army came storming through mutilating, and raping (see rape of Berlin) everything was when the Nazis said: "Aww, fuck..." ... and there are historical reasons that go even before WW1 that play a part in that. That's for another discussion though. Personally, I think the Brits don't get enough credit for their victory during The Blitz... That's just my humble opinion.
Long story short; USA was victorious, but did not win (meaning single-handedly) the war. That's all, folks.
Long story short; USA was victorious, but did not win (meaning single-handedly) the war. That's all, folks.