In Mapping Tweets in Africa, Simon Rogers wrote:

Who uses Twitter in Africa – and where are they based? Mark Graham and the team at the Oxford Internet Institute have looked at Tweets from key African cities – and the variation tells you a lot about access to technology across the continent. Just look at the variation between Johannesburg and Mogadishu. The data is not normalised for population but it still provides a unique insight.

I’ve used screenshots of the maps created by Mark Graham and Floating Sheep to re-create a single image, below, that allows you see the difference between the cities. The maps represent Johannesburg (row 1 left), Lagos (row 1 right), Nairobi (row 2 left), Tunis (row 2 right), Accra (row 3 left), Addis Ababa (row 3 right), Mogadishu (row 4 left) and Kigali (row 4 right).