During the years between the Civil War and World War II, police in New York City struggled with how to control a diverse city. In Police and the Empire City Matthew Guariglia tells the history of the New York Police to show how its origins were built upon and inseparably entwined with the history of race, ethnicity, and whiteness in the United States. Guariglia explores the New York City Police Department through its periods of experimentation and violence as police experts import tactics from the US occupation of the Philippines and Cuba, devise modern bureaucratic techniques to better suppress Black communities, and infiltrate supposedly unknowable immigrant neighborhoods. Innovations ranging from recruiting Chinese, Italian, or German police to form "ethnic squads," the use of deportation and federal immigration restrictions to control local crime--even the introduction of fingerprinting--were motivated by attempts to govern a multiracial city. Campaigns to remake the police department created an urban landscape where power, gender, sexuality, race, ethnicity, crime, and bodies collided and provided a foundation for the supposedly "colorblind," technocratic, federally backed, and surveillance-based policing of today.