Washington County is a county located in the U.S. state of Vermont. Named after George Washington, its shire town is the city of Montpelier and the most populous municipality is the city of Barre. As of the 2020 census, the population was 59,807, making it the third-most populous county in Vermont, but the third-least populous capital county in the United States after Hughes County, South Dakota and Franklin County, Kentucky. Washington County comprises the Barre, Vermont micropolitan statistical area. In 2010, the center of population of Vermont was located in Washington County, in the town of Warren.

Vermont is a landlocked state in the New England region of the Northeastern United States. It borders Massachusetts to the south, New Hampshire to the east, New York to the west, and the Canadian province of Quebec to the north. As of the 2020 U.S. census, the state had a population of 643,503, ranking it the second least populated U.S. state ahead of Wyoming. It is the nation's sixth smallest state in area. The state's capital of Montpelier is the least populous U.S. state capital. No other U.S. state has a most populous city with fewer residents than Burlington. Vermont is also well known for being the largest producer of true maple syrup in the United States for over 200 years.