Urbanization, rising income inequality, and increasing class segregation have produced a geographic concentration of affluence and poverty throughout the world, creating a radical change in the geographic basis of human society. As the density of poverty rises in the environment of the world’s poor, so will their exposure to crime, disease, violence. and family disruption. Meanwhile the spatial concentration of affluence will enhance the benefits and privileges of the rich. In the twenty-first century the advantages and disadvantages of one’s class position will be compounded and reinforced through ecological mechanisms made possible by the geographic concentration of affluence and poverty, creating a deeply divided and increasingly violent social world.