In their book, The Triumph of Injustice: How the Rich Dodge Taxes and How to Make Them Pay, economists Emmanuel Saez and Gabriel Zucman lamented the retreat of the United States’ tax system from its heyday between the 1930s and 1970s when it was, in their words, “perhaps the most progressive in world history.”1 As seen in Figure I.1, the top rate shot up from 25 percent after World War I to more than 60 percent in the early 1930s and settled at the astronomically high rate of 91 percent for over a decade between 1951 and 1963. That turned out to be the high point for the top marginal rate. Over the next several decades the rate dropped to 70 percent, then 50 percent, and finally a low of 28 percent in the late 1980s. Although it has crept up since then, the top rate has never approached anything close to what it was at mid-century, remaining below 40 percent for the last four decades.