...a rate which almost nobody actually paid, given the copious methods for reducing tax liability available at the time (most of which have since been eliminated).
- During WWI it peaked at 77%
- During WWII it peaked at 94%!!
Capital gains -- the rate the upper class actually pays -- has never risen above 35% at the federal level. And that's within a few points of 2018 marginal rates when we factor in state level taxes for places like California. The tax moved from federal to state (or to earmarked federal, like NIIT)
1945: 35% federal + 6% state = 41%
2018: 25% federal + 3.8% NIIT + 13.1% state = 41.9%
Prior to losing SALT, wealthy Californians paid slightly lower marginal rates than in 1945. Trump's changes cause the current marginal tax rate for wealthy Californians to be higher than in 1945 -- the year you're calling out as a peak.
No one really paid 94%.
The bulk of the interstate highway system was built between 1960 and 1980.
The percentage of GDP collected as income taxes is about the same then as it is now. In fact, the top 1% paid less of the total taxes during the New Deal than now.