Northerners (Yankees) were once against slavery, but their majorities now favor slavery to the state.
Not New York City. They profited handsomely from the trade.
The worst race riot in American history, by far, took place in New York City during and after the Battle of Gettysburg. A substantial number of black people who were unlucky enough to find themselves in the streets during those days were lynched on the spot.
The mayhem didn't end until union troops arrived from Gettysburg to end it