The flag, which was adopted in 1919, has five alternating green and white bars that symbolize the five boroughs. In the left corner are 24 white stars on a field of blue. The blue field represents the department, and 23 of the stars represent the separate towns and villages that became part of New York City in the consolidation of 1898.
The 24th star represents the city itself. Green is a traditional police color associated with the department since the time of the Dutch; it does not stand for Ireland.