Source: The Truth About Taxes: Here's How High Today's Rates Really Are
"Importantly, this was one of the most successful eras in US economic history [the 1950s and early 1960s]. The middle class boomed, the economy boomed, and the stock market boomed. And all with the top marginal income tax rate over 90%."
"Super-low tax rates on rich people also appear to be correlated with unsustainable sugar highs in the economy - brief, enjoyable booms followed by protracted busts. They also appear to be correlated with very high inequality. (For example, see the 1920s and now)."