As income inequality in the United States has reached an all-time high, commentators from across the political spectrum warn about the social implications of these economic changes. America, they fear, is “coming apart” as the gap between the rich and poor grows into a fault line. This paper provides a comprehensive review of empirical scholarship in sociology, education, demography, and economics in order to address the question: How have five decades of growing economic inequality shaped America's social landscape? We find that growing levels of income inequality have been accompanied by increasing socioeconomic segregation across (1) friendship networks and romantic partners, (2) residential neighborhoods, (3) K-12 and university education, and (4) workplaces and the labor market. The trends documented in this review give substance to commentators' concerns: compared to the 1970s, rich and poor Americans today are less likely to know one another and to share the same social spaces. The United States is a nation divided.