Calais is a city in Washington County, Maine, United States. As of the 2010 census, it had a population of 3,123. The city has three United States border crossings (also known as ports of entry) over the St. Croix River bordering St. Stephen, New Brunswick, Canada. Calais has been a city of commerce and is recognized as the primary shopping center of eastern Washington County and of Charlotte County, New Brunswick. Retail, service, and construction businesses are the primary components of the Calais economy.