WWII destroyed china, europe, korea, and japan. That left the US as the sole manufacturing base. It was easy to kick ass when all your competitors destroyed themselves.
The US can be economically dominate again. All we have to do is get germany to invade russia and bomb the heck out of everyone else, then we need to get japan to invade china and korea and then we need to drop a couple of nukes on japan and all will be right with american manufacturing again.