Under that constitution, Wisner was a member of the state senate from 1777 until 1782. After the war he remained active in civic affairs. In 1784, he founded an Academy in Goshen, and was one of the regents of the University of the State of New York from 1784 to 1787. In 1788, Wisner was a delegate to the state convention called to ratify the U.S. Constitution. He was one of those who opposed ratification, fearing that the strong central government would eventually infringe on state and individual rights. Wisner died at home in Goshen in 1790. He was buried in the Old Wallkill Cemetery in Wallkill, New York. Wisner married Sarah Norton in 1739. His son Gabriel, born 1754, died in 1779 in the Battle of Minisink. He married Elizabeth Waters and had three children. His daughter, Sarah Wisner (1745–1810), married Major Moses Phillips (a descendant of the Rev, George Phillips, the Winthrop family through Elizabeth Fones, and Thomas Cornell (settler)), with whom he made gunpowder for George Washington. Moses Wisner, a collateral descendant, was the 12th Governor of Michigan. Charles F. Brush, inventor and commercializer of the arc lamp and founder of a predecessor firm of General Electric, is a great great-grandson.