river in western Africa, rising 25 miles (40 km) north of Kindia in the Fouta Djallon highlands of western Guinea. It marks 63 miles (101 km) of the Guinea–Sierra Leone border before entering Sierra Leone to complete its 160-mile (257-kilometre) course to the Atlantic Ocean. Its lower reach (in Sierra Leone) flows through a densely populated mangrove swamp area that has been extensively cleared for rice cultivation by the Temne people. Three towns on the river—Kambia (30 miles 【48 km】 upstream at the head of navigation), Rokupr (site of the West African Rice Research Station), and Mambolo (site of a government rice mill)—are the chief collecting centres for the swamp rice, which is transported downstream and coastwise to Freetown by launch. The People's Republic of China, in the mid-1970s, financed two bridges to replace the ferries over the Great Scarcies and Little Scarcies rivers at Kambia and Mange. Fishing and the preparation of salt are important activities near the river mouth.