Windsor is a town in Windsor County, Vermont, United States. As the "Birthplace of Vermont", the town is where the Constitution of Vermont was adopted in 1777, thus marking the founding of the Vermont Republic, a sovereign state until 1791, when Vermont joined the United States. Over much of its history, Windsor was home to a variety of manufacturing …Windsor is a town in Windsor County, Vermont, United States. As the "Birthplace of Vermont", the town is where the Constitution of Vermont was adopted in 1777, thus marking the founding of the Vermont Republic, a sovereign state until 1791, when Vermont joined the United States. Over much of its history, Windsor was home to a variety of manufacturing enterprises. Its population was 3,559 at the 2020 census.