The metaphor of the melting pot is unfortunate and misleading. A more accurate analogy would be a salad bowl, for, though the salad is an entity, the lettuce can still be distinguished from the chicory, the tomatoes from the cabbage.
Racism is when you have laws set up, systematically put in a way to keep people from advancing, to stop the advancement of a people. Black people have never had the power to enforce racism, and so this is something that white America is going to have to work out themselves. If they decide they want to stop it, curtail it, or to do the right thing … then it will be done, but not until then.