At least two factors can be credited for the reemergence, within contemporary public discourse, of debate about domestic US inequality. Most often cited, and emphasized in chapter 1, are the trends that reveal steady increases in income and wealth inequality since the early 1970s. In contrast to the first quarter century of the postwar period (1945–70), in which substantial real income gains were experienced by all economic levels and demographic groups, the past three decades have yielded only a small rise in median income for the population as a whole, while a disproportionate share of income and wealth gains have gone to the “top” 10 percent of the population. Further, analysts have asserted that many of these small gains can be attributed to rising work hours experienced particularly by women in the workforce.

A second factor also bears consideration. In an era of globalization, analysts and citizens increasingly have seen that, among “developed” nations, the United States experiences the highest level of income inequality. Stated differently: nations with similar levels of “human development” – most with lower per-capita incomes but with competitive or superior educational and health indicators – experience significantly less income inequality. For the world as a whole, the United States' degree of income inequality is surpassed by only the most unequal developing nations, including most Latin American nations, Thailand, and South Africa. Comparisons among nations can be problematic since they differ in terms of degree of homogeneity, limitations on economic and other kinds of freedom, and so on.