xbuzzerx
CE&P Secret Police
The term "Caucasian" refers to a mountain range in Eastern Europe where it is believed that the first Indo-Europeans settled. Considering most white Americans feel no affinity for Eastern Europe at all, it seems very PC from our side of the fence.
Well... there are a lot of other reasons as well. Not all caucasians are included in white, even if all whites are caucasian. East Indians, hispanics, etc. All very different categories on forms, and in social perception, than "white", even though they are also caucasian. The U.S. has a very special relationship with whiteness, not caucasianness, in its legal history. Laws did briefly embrace the anthropological caucasian argument until the first East Indian applied for whiteness in the courts.

