What evidence does Krugman provide for the prevalence of economic inequality in US society?

Paul Krugman highlights several pieces of evidence to illustrate the prevalence of economic inequality in the U.S., including rising income shares for the top 1% and stagnating wages for the middle and lower classes. He often cites data showing that wealth concentration has increased significantly over the past few decades, with the richest households accumulating a disproportionate amount of national wealth. Additionally, he points to disparities in access to education and healthcare as further indicators of systemic inequality in American society.