The Lualaba River flows entirely within the eastern Democratic Republic of Congo. It is the greatest river source (headstream) of the Congo River by volume of water. The Lualaba is 1,800 kilometres (1,100 mi) long. Its headwaters are in the country's far southeastern corner near Musofi and Lubumbashi in Katanga Province, next to Zambia. The Chambeshi River is the longest river source (headstream) of the Congo.