What are the positive effects of imperialism in Africa?
If you were to call the effects of any kind of imperialism as positive, it would be more in the sense of considering it to be the "white man's burden" to civilize the developing world.
It cannot be denied that in geographical areas around the World, like Africa, Asia, Australia, there were only small states created by individual tribes and due to the result of the animosity between them progress was slow and limited. But that was the situation that Europe was in to start with, wasn’t it?
Imperialism never had an objective of benefiting the areas that were being conquered. It was always done in the quest of resources, like mineral wealth, land, laborers, resources from animals and plants that were in short supply, etc.
If one were to look at civilizations around the World before they were imperialized, a majority of them had a great amount of knowledge of science, mathematics, technology, medicine, etc. Examples abound to prove this.
Similarly, in Africa, though one could say that progress has been limited to only a few nations and this was mainly the effects of Imperialism, and in most of the continent the areas which have been freed are now in a dire state, it would not be entirely correct to give Imperialism all the credit.
If the continent had been left alone, eventually the small states would have consolidated and grown larger; there would have been a reduction in tensions between them; and the results helped by the immense natural resources available in the continent would have resulted in tremendous progress.