It is a simple matter to prove America grew by leaps and bounds in the 50's and 60's IN SPITE of the record high taxes. This is because of a little thing called "cause and effect." World War II ended in 1945. It devastatedc Japan, Germany and virtually all of Europe. The only manufacturing country in the world whose infrastructure was untouched was America. During the 50's and 60's, America was the ONLY player of any consequence. It would be absurd to think we could NOT have experienced record growth. When you have a monopoly of manufacturing all the goods the world uses, you can't help buy get rich, no matter WHAT the tax rate might be.
Pay heed, folks - the liberals use this kind of deception all the time. They never, ever lay anything where it belongs. They say high taxes are responsible for growth, just because high taxes happened to be in place when growth could not be stopped. They claim Democrats passed the Civil Right Act because LBJ signed it into law, in spite of the fact that a much higher percentage of Republican lawmakers passed it while a much higher percentage of Democrats opposed it - in fact, Senator Byrd personally filibustered the act. And Democrats give themselves credit for the rapid growth of the late 90's, in spite of the fact that the growth occurred from the Republican Contract With America - it was a Republican controlled Congress that made the laws that Clinton signed.
So, when you hear a Democrat try to claim that high taxes resulted in growth during the 50's and 60's, you can tell them the truth - that the growth occurred IN SPITE of high taxes, not because of them. And you can educate them about "cause and effect" of a devastating European war that made us Top Dog.