Same situation in Sacramento. If you ride Amtrak east, you go through miles of trash left by “the homeless”. Actually the RR will clean it up and in months, thanks to the liberal policies of CA, it’s as bad as ever. Then they spend millions on a bike trail and allow the “homeless” (aka America’s Most Wanted) to camp out on it.
I saw this outside of NYC, but it appeared that most of the trash was tossed down embankments from adjacent roads. I figured that it wasn't due to the homeless but just dumping from people that didn't have garbage service.