Rules and Regulations for Day and Night Police of the City of New York; with Instructions as to the Legal Powers and Duties of Policemen, printed in New York by Casper C. Childs, 1846. The New York City Police Department was established on May 23, 1845, with an initial 900 men, at a time when New York had nearly 400,000 people. This was the first time a policing body in New York was given an official book of regulations. 3 7/8" x 6".