
10/13/2025
The S**o River (/ˈsɑːkoʊ/ SAH-koh; Abenaki: Sαkóhki) flows through northeastern New Hampshire and southwestern Maine in the United States. It drains a largely rural basin covering 1,703 square miles (4,410 km²) of forests and farmland west and southwest of Portland, before emptying into the Atlantic Ocean at S**o Bay, about 136 miles (219 km) from its source.
The river provides drinking water to around 250,000 people across 35 towns, and historically served as a key route for transportation and water power, helping spur the growth of the cities of Biddeford and S**o, as well as the towns of Fryeburg and Hiram.