As policymakers reckon with how the United States became a global leader in imprisonment after World War II, scholars have suggested that the roots of this phenomenon are in conservative backlash to postwar crime or in federal intervention in American cities during the urban crisis. However, historians and social scientists have overlooked the role of jails in the origins story of mass incarceration. Through a close historical examination of Cook County Jail in Chicago, my research addresses how policymakers used reform claims to rationalize the growth of large urban jails from the 1950s through the 1990s. As a massive state building project, mass incarceration was contingent upon branding urban jails as providers of social services and rehabilitation, even though there was proof that jails failed to provide such services and as jail policymakers built bigger and more brutal jails. While activists, lawyers, and prisoners challenged dehumanizing conditions and state violence, jailers responded to public scrutiny by assuring the public that Cook County Jail was in the process of becoming a space that was beneficial to people awaiting trial there. This project locates the emergence of the contemporary carceral crisis in the battle to transform America’s jails. / History