FDR, didn't create it:
1) America was the last country in the world to leave the depression, y? Because FDR implemented socialist views which only made the situation worse, only god knows how he stayed in power 4 13 years. What made america the power was the war the followed:
1) The Nuke was invented in Germany, so in theory the Germans should of won, however the inventor was jewish, so moved across the sea, where he got accepted into the states, he went on to lead the Manhattan project. This is what gave the US their power
2) Winning a war from a distance makes u powerful 1) no infrastructure damage 2) easier riches