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.

Machias is a town in and the county seat of Washington County in Down East Maine, United States. As of the 2020 census, the town population was 2,060. It is home to the University of Maine at Machias and Machias Valley Airport, a small public airport owned by the town. The word Machias roughly translates in Passamaquoddy as "bad little falls", a reference to the Machias River. Machias was the site of the first naval battle of the American Revolution.