Calais is a city in Washington County, Maine, United States. As of the 2020 census, it had a population of 3,079, making Calais the third least-populous city in Maine. The city has three Canada–US border crossings over the St. Croix River connecting to St. Stephen, New Brunswick, Canada.

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.