Harpswell is a town in Cumberland County, Maine, United States, within Casco Bay in the Gulf of Maine. The population was 5,031 at the 2020 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.

Cumberland County is a county in the U.S. state of Maine. As of the 2020 census, the population was 303,069, making it the most populous county in Maine. Its county seat is Portland. Cumberland County was founded in 1760 from a portion of York County, Province of Massachusetts Bay, and named for William, Duke of Cumberland, a son of King George II. Cumberland County has the deepest and second-largest body of water in the state, Sebago Lake, which supplies tap water to most of the county. The county is the state's economic and industrial center, having the resources of the Port of Portland, the Maine Mall, and having corporate headquarters of major companies such as Fairchild Semiconductor, IDEXX Laboratories, Unum, and TD Bank. Cumberland County is part of the Portland–South Portland, ME Metropolitan Statistical Area.