Gosh... that's a bit tougher... I tend to recall reading that there was a similar argument at the time amongst scholars of the day though, so you might be able to find some good stuff in educational journals of the day, if you can get access to them. I'm not sure it's such a fair question because yes, America was dominant post WWI, but we kinda had our chair yanked from under us with the Great Depression. The fair was more about "gray skies are gonna clear up" than "we're number 1"