The National Fraternal Order of Police (FOP) is a fraternal organization consisting of sworn law enforcement officers in the United States. It reports a membership of over 355,000 members organized in 2,100 local chapters (lodges), state lodges, and the national Grand Lodge. The organization attempts to improve the working conditions of law enforcement officers and the safety of those they serve through education, legislation, information, community involvement, and employee representation.

Police unions in the United States include a large number and patchwork variety of organizations. Of those unions which conduct labor negotiations on behalf of its police members, 80% are independent and have no affiliation to any larger organized labor groups. There were a reported 800,000 sworn officers in the United States as of 2017, and an estimated 75–80% of them belonged to a union.