Niger River, a river of western Africa. It is 2,600 miles (4,200 km) long, the third longest in Africa (after the Nile and the Congo). It drains an area of about 730,000 square miles (1,890,700 km2).
The Niger begins in southern Guinea near the Sierra Leone border and flows in a great arc northeastward into Mali, skirting the edge of the Sahara before turning southeastward and flowing through Niger and Nigeria. It empties into the Gulf of Guinea through a broad delta. The Niger has only one large tributary—the Benue in Nigeria. Torrential rains in the lower part of the Niger's basin cause an enormous flow into the delta. In contrast, the upper and middle courses, crossing arid to semiarid land, carry relatively little water.
Although it is one of Africa's major rivers, the Niger is of little economic importance. Navigation is limited because of numerous rapids and shallows; irrigation projects tapping its flow are small and few in number. Only Nigeria's Kainji Dam is a major producer of electric power.