The twin cities of Saco and Biddeford are located on the Saco River about 15 miles (24 km) south of Portland. After Lewiston/Auburn, they have in the past formed Maine's second most important industrial center, manufacturing primarily textiles and shoes. Remaining buildings in the old industrial center on Factory Island, including York Mills, are being renovated into offices, residences, and an educational facility. Most of Saco's industry was located on Factory Island, leaving most of the city with a residential character.
European settlement dates to 1630. Many French Canadians found work in the mills here during the 19th and early 20 centuries. Changing economic patterns have led Saco to become a bedroom community for nearby Portland.