Modern American policing did not begin on a single date or with the creation of one police department. Instead, policing in the United States developed gradually from a variety of local institutions and practices.

During the colonial period, communities relied on sheriffs, constables, night watches, and other informal or semiprofessional systems to maintain order. As American cities grew during the nineteenth century, however, these systems became increasingly inadequate for rapidly expanding urban populations.

Boston established a professional daytime police force in 1838, while New York City developed a unified municipal police organization during the 1840s. Similar departments soon appeared in other major cities. These developments marked the emergence of what most people today would recognize as modern municipal policing.

American policing also has regional histories that cannot be ignored. In the South, slave patrols operated before the Civil War and were used to control enslaved populations, enforce restrictions on movement, and apprehend people attempting to escape slavery. Understanding American policing therefore requires examining several historical institutions rather than attempting to trace every modern police department to a single origin.

As police departments became established during the nineteenth century, officers generally worked on foot and maintained close relationships with their neighborhoods. Police provided far more than crime enforcement. Officers frequently addressed disorder, homelessness, public intoxication, disputes, missing children, public-health concerns, and other community problems.

Political influence, however, was often extensive. Hiring and promotion could depend upon political loyalty, and corruption was a persistent problem in many departments.

These shortcomings eventually generated a reform movement emphasizing professionalism, centralized administration, civil-service standards, training, technology, and greater independence from political machines.

Policing scholars George Kelling and Mark Moore later described the evolution of American policing through three broad strategic eras: the Political Era, Reform Era, and Community Policing Era.

Modern law enforcement incorporates elements developed throughout this history. Today's agencies use professional training, advanced investigations, communications technology, forensic science, data analysis, community partnerships, and problem-solving strategies that would have been unimaginable to nineteenth-century police officers.

Yet one principle has remained remarkably constant: policing ultimately occurs within communities. Understanding where policing came from helps students understand why modern police organizations operate as they do — and why the profession continues to evolve.

Kelling, G. L., & Moore, M. H. (1988). The evolving strategy of policing. Perspectives on Policing, No. 4. National Institute of Justice.

Walker, S., & Katz, C. M. (2012). The Police in America: An Introduction (8th ed.). McGraw-Hill.

U.S. Department of Justice, Office of Community Oriented Policing Services. (2014). Community Policing Defined.