Chicago Police Department

The Chicago Police Department, also known as the CPD, is the principal law enforcement agency of Chicago, Illinois, under the jurisdiction of the mayor of Chicago. It is the largest police department in the U.S. Midwest and the second largest in the nation (with 13,619 sworn officers and 2,625 other employees as of 2003), and one of the oldest organized police forces in the world. Currently, the Chicago Police Department is nationally accredited by the Commission on Accreditation for Law Enforcement Agencies.

Technological advances

• 1861, Police Patrol and Signal Service established with call boxes erected throughout Chicago so police officers could contact each other and respond to emergencies more efficiently
• 1884, Rogues' Gallery established to aid in the identification of suspects using the Bertillon system, taking exact physical measurements of arrested persons
• 1905, Murder Bureau established to use photography in solving crimes; fingerprinting was used to aid in the identification of suspects for the first time
• 1906, police cars were first used instead of horse-mounted patrols
• 1915, police department becomes completely motorized
• 1929, Chicago Tribune outfits the police department with one-way radio transmitters in squad cars
• 1932, calls were routed through centralized switchboards to facilitate efficient communication
• 1934, Accident Prevention Bureau established to aid in the protection of citizens as automobiles gained popularity and began taking over the streets of Chicago
• 1938, Scientific Crime Laboratory established as the police were finally allowed to pursue criminals using latest scientific methods being introduced to the world
• 1942, two-way radios were introduced
• 1947, squad cars were replaced by a combination ambulance and prisoner wagon called a squadrol
• 1952, walkie-talkie telephones were introduced; point-to-point communication systems allowed the police department to collaborate with county and state police
• 1957, Bureau of Identification established to use telephoto transmission to send photographs, fingerprints, and other pertinent data to police departments