Fairfax is a town in Franklin County, Vermont, United States, with a population of 5,014 at the 2020 census. The New England town of Fairfax is in southern Franklin County and is bordered by Chittenden County to the south. According to the United States Census Bureau, the town has a total area of 40.4 square miles, of which 39.8 square miles is land and 0.5…Fairfax is a town in Franklin County, Vermont, United States, with a population of 5,014 at the 2020 census. The New England town of Fairfax is in southern Franklin County and is bordered by Chittenden County to the south. According to the United States Census Bureau, the town has a total area of 40.4 square miles, of which 39.8 square miles is land and 0.58 square miles, or 1.44%, is water. The Lamoille River, a tributary of Lake Champlain, flows from east to west across the southern part of the town, passing through the communities of Fairfax and Fairfax Falls.