Harpswell is a town in Cumberland County, Maine, United States, within Casco Bay in the Gulf of Maine. The population was 4,740 at the 2010 census. Harpswell is composed of land contiguous with the rest of Cumberland County, called Harpswell Neck, as well as three large islands connected by bridges: Sebascodegan Island, Orr's Island, and Bailey Island and over 200 smaller islands. Harpswell is part of the Portland?South Portland?Biddeford, Maine Metropolitan Statistical Area.