why does racial discrimination exist in USA?

American racial discrimination dates back to European slave trade period。A report on human rights situation in the United States issued on Thursday said that racial discrimination is a deep-rooted social illness in that country as blacks and other minor ethnic groups are living in the bottom of the American society
1. Race should not be distinguished by fit and unfit quality,but social development should be distinguished by fast and slow speed.When a nation’s civilization is higher than another nation’s,the former will have a feeling of superiority over the latter.This is one of the main causes of human historical racial discrimination.Cultural、historical and political factors are the sources of American black racial discrimination.In the social class country,the discriminatory problem is also the social class problem.When a class is higher than another class,there must be some conflits and contradictions,as well as other series of problems.As the time goes by,it must form disc