I agree, at least partially. The U.S. had half the world's GDP at the end of WWII, most other advanced economies had their manufacturing base bombed to smithereens. The couple decades after the war were boom times in the U.S. And an anomaly. This was surely one of the bigger factors amid several.
>>mikem1+(OP)
Yep, green field with little competition, with massive scientific advances & unharmed industry after the war, educated populace, giant labour force, new overseas territories == huge boom.