Chittenden County (/ˈtʃɪtəndən/) is the most populous county in the U.S. state of Vermont. As of the 2010 census, the population was 156,545. The county's population estimate for 2018 was 164,572. The county seat is Vermont's most populous municipality, the city of Burlington. The county has over a quarter of Vermont's population and more than twice the population of Vermont's second most populous county, Rutland. The county also has more than twice the population density of Vermont's second most dense county, Washington. The county is named for Vermont's first governor and one of the framers of its constitution as an independent republic and later U.S. state, Thomas Chittenden.