The origins of American policing can be directly linked to its English heritage, particularly in the areas of community policing, crime prevention, the posse, constables, and sheriffs. During the 18th and 19th centuries the growing problems of urban centers led to the development of full-time uniformed police in both England and the United States. The preventive approach to law enforcement became central to the police role in both London and American cities. During the latter part of the 19th century police activity varied from one city to another depending on the local government and the political factions in power. Patrol officers were paid well but had poor job security and no training. Major corruption occurred in many police departments. A reform effort emerged toward the end of the 19th century. From 1890 to 1920 the reformers of the Progressive Era tried to carry out social, economic, and political changes in the cities, including changes in police departments. A second reform movement emerged in the failure of the Progressives, with efforts to professionalize the police with the assistance of leadership and technology. In the 1960's policing in the United States experienced its most serious crisis in its efforts to deal with disorders and riots associated with the rise in crime, the civil rights movement, and anti-war sentiment. The events of the 1960's forced the police, politicians, and policymakers to reassess law enforcement and the unintended consequences of the movement toward professionalism. The resulting analyses have made social science research an important part of policymaking decisions. Footnotes and 24 references.