The longest river in West Africa is the river Niger. It is approximately 4,180 km (2,600 mi) long and runs through five West African countries: Guinea, Mali, Niger, Benin, and Nigeria. The river Niger is an important source of water, transportation, and irrigation for millions of people living in these countries. It also supports a diverse range of flora and fauna and is an important natural resource for the region. The river Benue is a major tributary of the river Niger and is the second-longest river in West Africa. The river Volta and Senegal are not as long as the river Niger and are located in different regions of West Africa.