Colchester is a town in Chittenden County, Vermont, United States. The population was 17,067 as of the 2010 census. It is the fourth-most populous municipality and second-most populous town in the state of Vermont. Colchester borders Burlington–Vermont's most populous municipality– to its south . The town is directly to Burlington's north on the eastern shore of Lake Champlain, to the west of the Green Mountains. The Vermont National Guard is based in the town, and it is also home to Saint Michael's College and the Vermont campus of Southern New Hampshire University.