South Portland is a city in Cumberland County, Maine, United States, and is the fourth-largest city in the state, incorporated in 1898. As of the 2010 census, the city population was 25,002. 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, rail, and highway transportation options, the city has become a center for retail and industry in the region.

Despite the name, South Portland was never part of the city of Portland, but rather part of Cape Elizabeth. It broke off in 1895. However, both Cape Elizabeth and Portland were once part of Falmouth. Cape Elizabeth, and by default, South Portland, broke away from Falmouth in 1765. South Portland is a principal city of the Portland – South Portland – Biddeford metropolitan area.

South Portland was first settled in 1630, and it grew to become a small residential community with many farms. The village was raided by natives in Father Rale's War (1724). In 1858, the City of Portland purchased land near the Fore River for the Forest City Cemetery. On March 15, 1895, it was incorporated as a town after it broke away from Cape Elizabeth, based on a disagreement on a future source of public drinking water. Three years later South Portland became a city, destined to receive its drinking water, like Portland, from Sebago Lake, while Cape Elizabeth used wells or other local sources.

On South Portland's waterfront is Fort Preble, which is a military fort established in 1808 to protect Portland Harbor. It was in operation during several American conflicts, including the United States Civil War, World War I, and World War II. Near Fort Preble is Spring Point Ledge Light, which was constructed by the federal government in 1897 to mark a dangerous rock ledge.

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