This session examines the construction of the segregated city by investigating how projects that aimed to modernize the cityscape and integrate city inhabitants into idealized and ideologically specific visions of urban life ended up demarcating privileged and marginalized spaces and populations within early twentieth-century cities. The development of Los Angeles’s water infrastructure, of Mexico City’s working-class neighborhoods, and of São Paulo’s main public park illustrate the good intentions of city planners, urbanists, and architectures who were eager to elevate cities and urban populations to newly imagined and globally informed standards of urban modernity, organization, and aesthetics. As the papers in this session show, their efforts, however, arbitrarily and selectively targeted different urban groups to be the beneficiaries or the sacrificial victims of their modernizing projects and vision. While their accomplishments were celebrated at the time by their political, ideological, and elite allies—and are sometimes still commemorated in narratives about these cities’ past—they left a legacy of social and racial segregation that must be acknowledged. By revisiting the history and legacy of these projects, the papers in this session together offer a comparative and global urban history perspective that expands our understanding of how the making of the modern city could produce enduring inequalities.