We live in a period when more people are migrating from the countryside to the city, from city to city, and from country to country than at nearly anytime in human history. At the same time, we see sharp increases in wealth and income inequality. These two trends fuel populist movements on both the left and right, topping political agendas across the world. Untangling the Political Roots of Immigration and Inequality in the United States examines the causes, consequences, and politics of mass migration and growing inequality by investigating the case of the United States – the quintessential immigrant nation. While scholars, policy makers, and advocates have put forth a variety of explanations, many misdiagnose the causes and put forward remedies that treat symptoms. This book looks to the root causes of mass migration and intensifying inequality, arguing that they are two sides of the same coin resulting from rapacious forms of capitalist accumulation and imperialist interventionism. Developing a broadly left analytic framework grounded in elements of Marxist theory and political science, two periods are examined – 1870–1925 and 1970–2025 – when the proportion of immigrants in the US peaked at 15% of the total population, the US experienced steep inequality and political polarization, immigration and inequality became contentious political issues that generated sharp conflict, and immigrants and workers organized mass movements that advanced radical politics and transformative change. This book contains a wealth of information and elevates valuable lessons for scholars, policy makers, and organizers interested in understanding these trends and forging equitable and just solutions today.