Recently The Tax Foundation looked into the commonly held belief that rich Americans used to pay much higher income taxes in the 1950s than they do today. It found that the difference between then and now isn’t actually that significant:

The data shows that, between 1950 and 1959, the top 1 percent of taxpayers paid an average of 42.0 percent of their income in federal, state, and local taxes. Since then, the average effective tax rate of the top 1 percent has declined slightly overall. In 2014, the top 1 percent of taxpayers paid an average tax rate of 36.4 percent.

The confusion may stem from the fact that the top marginal income tax used to be 91 percent. But the Tax Foundation found that the effective tax rate in the 1950s was 16.9 percent:

There are a few reasons for the discrepancy between the 91 percent top marginal income tax rate and the 16.9 percent effective income tax rate of the 1950s.

• The 91 percent bracket of 1950 only applied to households with income over $200,000 (or about $2 million in today’s dollars). Only a small number of taxpayers would have had enough income to fall into the top bracket – fewer than 10,000 households, according to an article in The Wall Street Journal. Many households in the top 1 percent in the 1950s probably did not fall into the 91 percent bracket to begin with.
• Even among households that did fall into the 91 percent bracket, the majority of their income was not necessarily subject to that top bracket. After all, the 91 percent bracket only applied to income above $200,000, not to every single dollar earned by households.
• Finally, it is very likely that the existence of a 91 percent bracket led to significant tax avoidance and lower reported income. There are many studies that show that, as marginal tax rates rise, income reported by taxpayers goes down. As a result, the existence of the 91 percent bracket did not necessarily lead to significantly higher revenue collections from the top 1 percent.

You can read the whole blog post here.