I disagree that "Gentrification" started in the 80's in NYC. It was the 80's that made it not a wasteland of abandoned or intentionally burned buildings due to improving finances for the city government itself. However the influx of transplants did not happen until the late 90's. Crime was still astronomical compared today until the mid 90's. It was still considered unsafe. Once the city was comparatively safer, the trend started which still continues today. Areas like Bushwick are now home to transplants from the midwest while 20-30 years ago they would never set foot in there.
Places like CBGB's held on until the 2000s. Working class people could still affordably live in most places in the city until then as well.
The 80s in NYC were still pretty bad although I suppose you could argue they stopped getting worse sometime around then. Yeah, I'd date improvement to the mid to late 90s. Boston probably about the same.
I lived in NYC for a summer in the mid-80s. I never set foot anywhere below about 90th in Manhattan.
You can actually pinpoint the moment in 1994 when the derivative changed. David Schwimmer goes from side character in season 1 of NYPD Blue who ends up dead trying to save an old lady from a mugger to...Ross.
Places like CBGB's held on until the 2000s. Working class people could still affordably live in most places in the city until then as well.