Here is an article from Wiki about Jersey. There were pockets of slavery in New England as well.
New Jersey banned the importation of slaves in 1788, but at the same time forbade free Negroes from elsewhere from settling in the state. [5] In the years following the American Revolution, the emphasis on legal equality and the rights of man caused legislators in some states to consider abolishing slavery. The New Jersey state legislature was the last in the north to do so, passing a law in 1804 for the gradual abolition of slavery. [6] The 1804 statute and subsequent laws freed only slaves born after the law was passed. Furthermore, African Americans had to serve lengthy apprenticeships to the owners of their mothers. Women were freed at 21, but men were not emancipated until the age of 25. Slaves born before these laws were passed were considered “apprenticed for life.”
Although at first New Jersey allowed African American men to vote, the legislature disfranchised them in 1807. In 1830 two-thirds of those enslaved in the North lived in New Jersey. It was not until 1846 that New Jersey completely abolished slavery. [5]Although slavery was abolished in 1846 by statute (”An Act to Abolish Slavery”), it was only a name change. [7] Former slaves were termed apprentices and were still subject to servitude to their owners. It was not until the Thirteenth Ammendment to the United States Constitution was passed that all forms of involuntary servitude were abolished in New Jersey.
Well, I stand corrected.