Why the increase in racial division?

“I had begun to see a new map of the world, one that was frightening in its simplicity, suffocating in its implications. We were always playing on the white man's court, Ray had told me, by the white man's rules. If the principal, or the coach, or a teacher, or Kurt, wanted to spit in your face, he could, because he had power and you didn't. If he decided not to, if he treated you like a man or came to your defense, it was because he knew that the words you spoke, the clothes you wore, the books you read, your ambitions and desires, were already his. Whatever he decided to do, it was his decision to make, not yours, and because of that fundamental power he held over you, because it preceded and would outlast his individual motives and inclinations, any distinction between good and bad whites held negligible meaning.” 
― Barack Obama, Dreams from My Father: A Story of Race and Inheritance