How to end racial divisions

For the last two days I subbed in Highland Park. Every student in each of my classes was African-American. I can not say that I have yet had an all Euro-American class. When I subbed at Mohawk Elementary School there were no African-Americans in my class, but there was one Aremnian girl (whose grandmother had been born in Egypt) and I think one girl whose ancestors were from China.
In most classes I had there were at least some African American students. Only in Chippewa Valley Schools of all six school districts I have subbed in has there been any class with no African-Americans. However, I think the highest diversity index has to go to Pontiac (at least if we use broad categories instead of specific ethnic groups like Albanians and Armenians). There were Hispanic, Asian, African-American and Euro-American students in my classes.
I am not sure how to end racial divisions, but I do have to say that at least among Mount Clemens Middle School students they seem to largely not exist. On the other hand I never saw them more present than among Mount Clemens High School students. I am not sure why this is. I would like to believe it is because we are coming closer to true unity, but fear it is because students in middle school have not been differentiated along racial lines as much as they have been by the time they reach high school.