Calais is a city in Washington County, Maine, United States. As of the 2010 census, it had a population of 3,123, making Calais the third least-populous city in Maine (after Hallowell and Eastport). The city has three Canada–US 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.
This area was occupied for thousands of years by indigenous peoples. The historic Passamaquoddy, an Algonquian-speaking people of the Wabanaki Confederacy, was predominant in this area at the time of European encounter and settlement.