The New York City Transit Police Department was a transit police department responsible for the protection of New York City Subway and bus lines, established in 1953. In 1936, Mayor Fiorello H. LaGuardia authorized the hiring of Special Patrolmen for the New York City Subway system; these patrolmen eventually became the Transit Police. In 1949, the department was officially divorced from the New York City Police Department, but was eventually fully re-integrated in 1995 as the Transit Bureau of the New York City Police Department by New York City Mayor Rudolph W. Giuliani. In 1997, the Transit Bureau became the Transit Division within the newly formed Transportation Bureau. In July of 1999, the Transit Division once again became the Transit Bureau. Headquarters for the NYPD Transit Bureau are located at 130 Livingston Street in Brooklyn Heights.

A main task of the Transit Police was its defense of the subway system from defacement. Graffiti was very prominent throughout the subway system by the mid-1980s and the city government took a hard line in response, though some saw it instead as a "social trend" and a sign of diversity. The Transit Police, and specifically a new unit called the Vandal Squad began to fine and arrest those painting graffiti. They also made a policy to remove any work of graffiti within 24 hours of its creation. By the end of the 1980s, the Transit Police had effectively solved the problem of graffiti in the New York City subway system.