Chicago Police DepartmentThe Chicago Police Department is the law enforcement agency of the U.S. city of Chicago, Illinois, under the jurisdiction of the City Council. It is the second-largest municipal police department in the United States, behind the New York City Police Department. It has approximately 12,000 officers and over 1,925 other employees. Tracing its roots back to the year of 1835, the Chicago Police Department is one of the oldest modern police forces in the world.