I don't think it has anything to do with the colour of the skin. Creationism tends to thrive with under-educated and highly religious communities, which often also goes in hand with economic difficulties. This targets both blacks and whites. Since black population tend to be less rural than whites, they are generally less at a risk though. (if someone had hard data though it'd help, as this is mostly speculation on my part)
The reason why we picture creationists as white is because those who write and propagate its rhetoric tend to be wealthy organisation sponsored by ultra-conservative and fundamentalist organisations with an agenda. They don't belong to the same social strata as the people they indoctrinate. I'm pretty sure a good chunk of those aren't actually ardent creationists themselves; they are just in it for the money. You can make an easy buck selling books and DVDs to gullible people too ignorant and credulous to realise every single of your arguments have been debunked decades ago.
The reason this doesn't happen in other Western countries is because those organisations didn't get a foothold (yet), and education tends to remain strong.