According to websites New York Historical Society (http://www.slaveryinnewyork.org/about_exhibit.htm) and NYSenate.gov (http://open.nysenate.gov/legislation/api/1.0/html/bill/S4738A), slavery was not abolished in New York State until 1827.
Legislation for the gradual abolition of slavery began in 1799, but the emancipation of all slaves did not become law until July 4, 1827.
Even so, until 1841, it remained legal for slave owners to bring slaves into New York and keep them there, in slavery, for as long as nine months. This was abolished in 1841 under the leadership of Governor William Seward, one of the founders of the Republican Party.
Thanks for that added information.