You would not be racist if you started a Irish, or German, to just use examples, pageant.
A white pageant, I am not saying you would be racist, but isn't that a little to general?
And before you say but blacks do it. That they don't break it down to a geographical area, like Irish or German, they do, African American.
They could probably break down even further, like Europeans do with Irish and German, but they can't, because they, for whatever reason, over the generations, lost their specific geographical identity when they were forced into slavery.