The problem is that the US as a nation was built on land stolen from others by genocide, and labour stolen from others by slavery. These are the only reasons it could ever reach the heights it did and hold the power it does. This racism is a core, inseperable ingredient of the US identity. A celebration of the USA and to some extent a celebration of capitalism are the celebration of some of the most unspeakable acts that a civilisation could undertake. Combine this with the chauvinistic rhetoric of US social politics, and is it any wonder that racism is such a big problem? Dare I say I see no solution so long as the USA as a concept maintains credibility. Note I'm focusing on the states because it's particularly easy. Europe has an equally large race problem, but I find it's slightly more nuanced, and slightly harder to define. As for the other continents, I don't feel like I know enough to confortably comment.
Of course it wasn't, that's why the race dialogue in Europe is very different. We very much still have a problem with racism, though.