The Jim Crow system was undergirded by the following beliefs or rationalizations:

• Whites were superior to Blacks in all important ways, including but not limited to intelligence, morality, and civilized behavior.

• Any sexual relations between Blacks and Whites would produce a mongrel race which would destroy America.

•  Treating Blacks as equals would encourage interracial sexual unions.

• Any activity which suggested social equality encouraged interracial sexual relations. 

• If necessary, violence must be used to keep Blacks at the bottom of the racial hierarchy.