Gabon has a population that is estimated at 1,545,255. Historical and environmental factors caused Gabon's population to decline between 1900 and 1940.Gabon has one of the lowest population densities of any country in Africa, and the fourth highest Human Development Index in Sub-Saharan Africa.
The main river in Gabon, Ogooue River, arcs across the entire country, with major tributaries including Ivindo and Mpassa. Its mouth is at Port Gentil, on the Atlantic Coast, and it originates in the Republic of the Congo.
Politics of Gabon takes place in a framework of a republic whereby the President of Gabon is head of state and in effect, also the head of government, since he appoints the prime minister and his cabinet.