There were concentrations of slaves as high in southern NY state as in any southern state then and States' Righters there included George Clinton, the beneficiary of their Masters' votes. At that time there was legalized slavery in almost all states.
This refers to the power structure supporting slavery north and south which was the core of the democrat party of that day, the anti-federalists not all of whom were from the south.
Well, careful with the overgeneralization. One of Jackson Turner Main's interests in studying the Antifederalists was to see whether he could discern a common thread of interest among them. He found interesting demographic divergences on different axes (e.g. professionals versus farmers), but they tended to vary from area to area. In South Carolina, the biggest planters, concentrated in the coastal counties, tended to adhere to Federalism, and as I posted above, they were able to deliver a solid vote for ratification -- notwithstanding, by the way, that they were definitely in the minority in the State, being vastly outnumbered by Antifederalist freehold farmers in the interior and "border" counties. It was a peculiarity of South Carolina politics, that something like a "rotten borough" system worked to leverage the votes of the landowners in the older, coastal counties to the disadvantage of the yeomanry in the interior.
After much parsing and prosopographic research and counting of heads in ratification conventions, author Main came down to one gross criterion as the predictor for final adhesion to the Federalist Constitution or the Antifederalist rejection caucus: whether one was a member of, or closely affiliated with, the commercial interests and classes of one's State and community. The fact that people tended to nominate as convention delegates educated men who owned property likewise worked to the Federalists' advantage, because even Antifederalists of this class tended to rally to the other members of their socioeconomic group, leaving their numerous humbler constituents at home holding the bag, and a few rationalizations about "best judgment" and promised amendments. Thus, as I noted earlier, both Adamses and John Hancock came across and voted for ratification, sometimes against their instructions.