The Congo is the largest river in Western Central Africa. Its overall length of 4,380 km (2,720 mi) makes it the second longest in Africa (after the Nile); the river and its tributaries flow through the second largest rain forest area in the world, only the Amazon Rainforest being (much) larger. The Congo also gives its name to the Democratic Republic of the Congo and Republic of the Congo, both countries lying along its banks. Between 1971 and 1997 the government of then-Zaire called it the Zaire River.
The sources of the Congo are in the highlands and mountains of the East Africa Rift, as well as Lake Tanganyika and Lake Mweru, which feed the Lualaba River, which then becomes the Congo below Stanley Falls.
The Congo flows generally west from Kisangani just below the falls, then gradually bends southwest, passing by Mbandaka, joining with the Ubangi River, and running into the Pool Malebo (Stanley Pool). Kinshasa and Brazzaville are on opposite sides of the river at the Pool, then the river narrows and falls through a number of cataracts in deep canyons, running by Matadi and Boma, and into the sea at the small town of Muanda.
The mouth of the Congo was visited in 1482 by the Portuguese Diogo Cão, and in 1816 a British expedition went up as far as Isangila. Henry Morton Stanley was the first European to navigate along the river's length and report that the Lualaba was not a source of the Nile as had been suggested.
Nearly the entire Congo is readily navigable, and railways bypass the three major falls, and much of the trade of central Africa passes along it, including copper, palm oil (as kernels), sugar, coffee, and cotton. It is also potentially valuable for hydroelectric power, and the Inga facility below Pool Malebo is the first to exploit the river.
Tributaries, in order going upstream: