Saco is a city in York County, Maine, United States. The population was 20,381 at the 2020 census. It is home to Ferry Beach State Park, Funtown Splashtown USA, Thornton Academy, as well as General Dynamics Armament Systems (also known by its former name, Saco Defense), a subsidiary of the defense contractor General Dynamics. Saco sees much tourism during summer months due to its amusement parks, Camp Ellis Beach and Pier, Ferry Beach State Park, and proximity to Old Orchard Beach.

Saco is part of the Portland–South Portland–Biddeford, Maine metropolitan statistical area. Saco’s twin-city is Biddeford.

This was territory of the Abenaki tribe whose fortified village was located up the Sokokis Trail at Pequawket (now Fryeburg). There was a settlement at the mouth of the Saco river, with homes and permanent cultivation, at the time of contact with Europeans in the early 1600s.

In July 1607, 500 warriors led by sakmow (Grand Chief) of the Mi’kmaq First Nations Henri Membertou attacked the village at present-day Saco, killing 20 of their braves, including two of their leaders, Onmechin and Marchin, leading to conflict that lasted until 1615.

In 1630 the Plymouth Company granted Thomas Lewis and Richard Bonython a charter to establish a town at Saco, with a deed that extended 4 miles (6.4 km) along the sea, by 8 miles (13 km) inland. Settled in 1631 as part of Winter Harbor (as Biddeford Pool was first known). The government of Maine, under Ferdinando Gorges, was based in the town from 1636 to 1653. It would be reorganized in 1653 by the Massachusetts General Court as Saco, which would be renamed Biddeford in 1718.

The settlement was attacked by Indians in 1675 during King Philip’s War. Settlers moved to the mouth of the river, and the houses and mills they left behind were burned. Saco lay in contested territory between New England and New France, which recruited the Indians as allies. In 1689 during King William’s War, it was again attacked, with some residents taken captive. Hostilities intensified from 1702 until 1709, then ceased in 1713 with the Treaty of Portsmouth. The community was rebuilt and in 1718 incorporated as Biddeford. Peace would not last, however, and the town was again attacked in 1723 during Dummer’s War, when it contained 14 garrisons. In August and September 1723, there were Indian raids on Saco, Maine and Dover, New Hampshire. But in 1724, a Massachusetts militia destroyed Norridgewock, an Abenaki stronghold on the Kennebec River organizing raids on English settlements. The region became less dangerous, especially after the French defeat in 1745 at the Battle of Louisburg. The French and Indian Wars finally ended with the 1763 Treaty of Paris.