Liberia is located in West Africa, bounded by Guinea, Sierra Leone, Cote D'Ivoire, and the Atlantic Ocean. It has a population of 3.6 million people belonging to 16 major tribes. Liberia has a unitary democratic republic government based on the US model with three branches of government. It is divided into 15 counties for administrative purposes, each headed by a county superintendent appointed by the president. Lower levels include statutory districts, districts, cities, towns, and a traditional system of paramount chiefs, clan chiefs, and town chiefs. The key government ministries are the Ministry of Planning and Economic Affairs and the Ministry of Internal Affairs.