Today’s wealth inequality is, in a sense, a return to the Gilded Age. In 1928, the economic divide was large: The bottom 90 percent of Americans earned 50.7 percent of all pretax income, while the top 1 percent earned 23.9 percent, according to research by Berkeley economist Emmanuel Saez. The Great Depression and World War II acted as equalizers, and by 1944, the bottom 90 percent earned 67.5 percent of income, while the top 1 percent earned just 11.3 percent. But that relative equality started to morph again in the 1970s and by 2012, the bottom 90 percent accounted for just 49.6 percent of all pretax income, while the top 1 percent held 22.5 percent. There are plenty of theories about what caused this reversal.