South Portland is a city in Cumberland County, Maine, United States, and is the fourth-largest city in the state. Founded in 1895, as of the 2000 census, the city population was 23,324. Known for its working waterfront, South Portland is situated on Portland Harbor and overlooks the skyline of Portland and the islands of Casco Bay. Due to South Portland's close proximity to air, marine and highway transportation options, the city has become a center for retail and industry in the region. South Portland is a principal city of the Portland–South Portland–Biddeford, Maine Metropolitan Statistical Area.