"New York City’s slave market was second in size only to Charleston’s [South Carolina]. Even after the Revolution, New York was the most significant slaveholding state north of the Mason-Dixon line. In 1790, nearly 40% of households in the area immediately around New York City owned slaves — a greater percentage than in any Southern state as a whole, according to one study. "In contrast to the image of large gangs working in cotton fields before retiring to a row of cabins, slaveholdings in New York State were small, with the enslaved often living singly or in small groups, working alongside and sleeping in the same houses as their owners. Privacy was scant, and in contrast to any notion of a less severe Northern slavery, the historical record is full of accounts of harsh punishments for misbehavior. “Slavery in the North was different, but I don’t think it was any easier,” Mr. McGill said. “The enslaved were a lot more scrutinized in those places, a lot more restricted. That would have been very tough to endure.”