8. The NYPD Uses a Color of the Day System to Identify Undercover Officers

Both uniformed and undercover officers patrol the streets of New York City. The color-of-the-day system started in the 1970s with the now-defunct Street Crime Unit of the NYPD. During the ’70s and ’80s, undercover officers would pose in high-risk areas as homeless people or plain-clothes civilians in order to mediate the rising crime throughout New York City. The color of the day is a signal that is worn to prevent friendly fire, and police officers continue to use this system. When undercover officers are on duty, they are required to wear an article of clothing in the designated color of the day to signify that they are with the police department.