Since the first decades of the French Protectorate in Morocco, experts and officials have sought solutions to a variety of urban crises—from housing and unemployment to public health and popular unrest—in large-scale, publicly financed housing and infrastructure projects. In the 1940s and 1950s, Casablanca’s colonial municipal government created a new zoning apparatus and engaged in the rapid construction of housing developments as a means of managing the multiplying informal settlements on the city’s periphery. The architects of these projects aimed to implant an ethics of restraint and intercommunal respect within what they described as an unruly urban landscape, characterized by tense and potentially explosive relations between Europeans, Moroccan Muslims, and Jews. This paper traces how Casablanca’s colonial municipal government attempted to incorporate local notions of danger, uncleanliness, and transgressive behavior into new urban regulations as a way of countering the threat of intercommunal violence and anticolonial unrest. Zoning laws and electrification projects embedded and materialized ethnic and religious differences between the city’s European, Muslim, and Jewish populations within the physical and legal infrastructures of urban life in Morocco. More than just a “laboratory for modernity” (Rabinow 1989), Casablanca’s new housing projects were a site where colonial planners and engineers working with local informants aimed to build Moroccan understandings of pollution and respectability into networks of pipes, wires, and regulations. Following the violent December 1952 urban revolt, colonial experts and bureaucrats worked to cast the uprising as a "technical problem”—a mismatch between the Casablanca’s physical and legal infrastructures and the social and ethnic landscape of the city itself. This paper contributes to an emerging scholarly discussion of the political lives of infrastructures in the Middle East and North Africa by asserting the need to take seriously the interplay of expert projects and knowledges with local categories and forms of moral reasoning. As sociotechnical systems, Casablanca’s urban infrastructures were not simply top-down constructions but also encompassed the political and ethical projects of a diverse array of urban actors: Moroccan labor activists, rural migrants, and European settlers as well as the central state. Drawing on archival records, technical documents, and newspaper accounts from Protectorate-era Morocco, I argue that state strategies for managing the threat of violence through zoning regulations and built infrastructures have had lasting impacts on social and material life in urban Morocco.