According to gunnar myrdal, america's dilemma was a conflict between:

I believe the answer is: American Values and American racial policies
American racial policies in the past often discriminated against the minorities while giving a lot of space to the race majority. (such as the segregation law)
This lead to the situation where it became really difficult for members of racial minorities to advance in American soicety.

Ongoing civil wars western roman empire finally collapsed476 c.e. romulus, the last of theroman  emperors in  the west, was overthrown by the germanic leader odoacer, who became the first barbarian to rule in rome. the order that the  roman empire  had brought towestern  europe for 1000 years was no more.