There are a lot of debates as to what the exact effects of colonialism were to the colonized countries, and especially to Africa. There were some positive benefits of colonialism, like roads, schools, hospitals, etc. But there were a tremendous amount of negatives for those countries too, and most of the "positive" aspects of colonialism werent designed to benefit the local Africans. One of the biggest examples is in terms of transportation. Generally the Europeans built roads and railroads, but they went from ports to the mines, factories, and resources of the country, bypassing all but the most important cities. So when they left, the countries could still move their goods to market, but lacked the infrastructure required to tie their people together politically, or bring developments into the wilderness.

At its most mild, colonialism didnt really do much to help the average African, and at the worst it worked aggressively to hurt Africans. In the Congo, the Belgian government attempted at every turn to squeeze out as much profit from its colony as possible. Their main crop was rubber, harvested from forest by locals who were impressed into service. Until Leopold II's death, his Congo used intimidation, fear, terror, and slavery to maximize profits. Women were held hostage to coerce men into working harder, towns and villages were burned seemingly at random to "motivate" the populace to harvest more rubber, and workers were beaten, tortured, and even killed if they didnt meet their quotas. Worst of all was the Force Publique, the local military and police force. Those men were recruited from the local population to provide the muscle for local "police" actions. But they were forced into a macabre system in which they were required to shoot their fellow Congolese. But the Belgians feared that the FP would just fire indiscriminately and not kill their countrymen. So they instituted a policy where every FP member could only get new bullets if they brought back the hand of somebody they killed. Hands became the currency by which the members of the FP avoided become victims themselves. This lead to FP parties which roamed the country carrying baskets of smoked hands, looking for more wherever, and however, they could find them.

The Congo is a really extreme example, and isnt completely typical of the colonial experiences in say Angola, Egypt, or Sudan. But to achieve a similar goal, the domination and exploitation of the mineral and human resources of Africa, every colonial European country instituted a system in which Africans were marginalized, discriminated against, and frequently brutalized. And the "benefits" of colonialism were tailor made to benefit Europeans and a select group of chosen Africans. The vast majority of the population was no better off under imperial rule than they were before.

Post-Colonialism has been equally difficult for many African countries because the term Post-colonialism itself is a bit of a misnomer. Many countries have gained their independence, and have become their own sovereign entities. But in many cases the colonizers never left, or were just replaced by Americans. During the Cold War, America and the West had little time for non-aligned nations, and less for pro-Soviet nations. We felt that it was better to have a staunchly anti-Communist pro-West leader than one who leaned towards the Soviets, or worse thought for themselves. After all, though formal colonialism is over the resources which made Africa so vital remained, and the West had a vital interest in maintain some control and influence on the continent to secure those resources. This led to support of a lot of bad guys, guys who were anti-democratic, who killed their own people, but who supported Western interests. As John Foster Dulles put it, "He may be a son-of-a-bitch, but he's our son-of-a-bitch." Its made it all really had for Africans to move past colonialism and develop their own independent agendas.