What was the New York City Clean Train Movement era?

The New York City Clean Train Movement was a phenomenon between the 1970s and the 1990s, where city residents took it upon themselves to clean individual subway cars using a variety of different tactics. There were different levels of involvement, from more extreme activists who completely painted over trains to more grassroots projects focused on cleaning trains in their local stations. One of the core differences between the Clean Train movement and graffiti culture is that the Clean Train movement was often endorsed and supported by the transit workers' union.