Vermont, which broke away from New York, abolished slavery outright in its constitution, dated July 8, 1777.
The relevant section is Chapter I, subtitled “A DECLARATION OF THE RIGHTS OF THE INHABITANTS OF THE STATE OF VERMONT”
I. THAT all men are born equally free and independent, and have certain natural, inherent and unalienable rights, amongst which are the enjoying and defending life and liberty; acquiring, possessing and protecting property, and pursuing and obtaining happiness and safety. Therefore, no male person, born in this country, or brought from over sea, ought to be holden by law, to serve any person, as a servant, slave or apprentice, after he arrives to the age of twenty-one Years, nor female, in like manner, after she arrives to the age of eighteen years, unless they are bound by their own consent, after they arrive to such age, or bound by law, for the payment of debts, damages, fines, costs, or the like.
After declaring its independence, Vermont existed as a free republic known as the Commonwealth of Vermont. It was admitted to the union in 1791, with a state constitution that also contained the slavery ban. The 1777 constitution entitles Vermont to claim to be the first U.S. state to have abolished slavery.
Did that mean that blacks in Vermont were treated as equals? Umm… It was complicated. Still, they were better off than their brethren in the South, for sure.
For further study: