 The highway passes through seven countries and five national capitals, and links regions of similar climate and environment which have cultural and trade links going back centuries.It is one of two east–west transnational links in West Africa and runs inland from and, for most of its length, roughly parallel to the Trans–West African Coastal Highway with a separation of about .The Trans-Sahelian Highway has a length of about running through Senegal, Mali, Burkina Faso, Niger, Nigeria, and the far northern tip of Cameroon, ending at Ndjamena just inside the western border of Chad.