Washington County is a county located in the U.S. state of Maine. As of the 2020 census, its population was 31,095, making it the third-least populous county in Maine. Its county seat is Machias. The county was established on June 25, 1789. It borders the Canadian province of New Brunswick. It is sometimes referred to as "Sunrise County" because it includes the easternmost point in the 48 contiguous United States.