New Jersey had slaves - they abolished the practice in 1804... but the process of emancipation was gradual, not too unlike New York. There was a process of indentured servitude for the children of slave mothers. The last slaves were freed in 1865 with the passage of the 13th amendment.
While it was north of the Mason-Dixon line, slavery wasn’t uncommon in New Jersey. From my middle school history classes, they mentioned big slave and ex-slave communities in and near New Brunswick and Paramus.
All of this does nothing for the idea of reparations, though... as none of those slaves are still alive.
Many indentured servants were white...
Parts of Nj were actually below the Mason/Dixon line.