(4) Four Antique Postcards depicting Calais, Maine. They include Calais Avenue,Falls on St. Croix River, Memorial Park, and an aerial view of the city. Three divided backs and one undivided back which is used. The other three are unused. Condition: These are original antique postcards, not a copy or reproduction. They are all in excellent condition. Comments: 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 (after Hallowell and Eastport). The city has three CanadaUS border crossings (also known as ports of entry) over the St. Croix River connecting to 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.