@Creole - Most black Americans are mixed if their ancestors were here during slavery. The average black person in America is almost 10 percent white and many are even more white than that. And it didn't all come from the Massa having a secret romance with a slave, or worse, raping a slave. A lot of it came from humans doing what humans will do when they see someone they like and it happened before, during, and after slavery - laws against mixing be danged.
A HUGE portion of southern whites that have been here since those days are also mixed and they have no clue about it - they think if any relatives are out there who are black then one of the men stepped outside but have no idea that they themselves are carrying 'black blood' so to speak. People were making babies by choice with one another since they got here.
As to most white folks being racist, I disagree. There are far too many who are but I don't think it's most and I think a LOT depends on how old they are.