River, western Africa.
It rises in Guinea and flows northwest across Mali, then west to the Atlantic Ocean, forming the border between Mauritania and Senegal. It is 1,020 mi (1,641 km) long. Its two major headstreams, the Bafing and Bakoye, meet in Mali to form the Sénégal proper. Dams control floodwaters and prevent the encroachment of saltwater during the dry season.