There is a persistent geographical myth that the Nile is the only river in the world that flows north. This is entirely false. Many rivers flow north, including the St. Johns River in Florida, the Red River of the North in the US/Canada, and the Ob River in Russia. Rivers flow 'downhill' due to gravity, and 'downhill' can be in any cardinal direction. The reason the Nile is often singled out is that it is the longest river in the world and its northward flow from the highlands of East Africa to the Mediterranean Sea is its most defining characteristic. In Ancient Egypt, the terms 'Upper Egypt' (south) and 'Lower Egypt' (north) were based on this flow, which can be confusing for those used to 'up' being north on a map.