[dantheman]

The expansion of the middle class has nothing to do with the top tax bracket. It has to do with industrialization before automation (lots of low/medium skill jobs that provided significant value), and the destruction of competition around the world.

[alnayyir]

Speaking more seriously, I'm pretty certain the expansion of the middle class was due to strong white labor unions and Fordism as a cultural subtype within Modernism.

This entailed many things, with which the top tax bracket had little to no relevance.