A person of the Caucasian race (6 Fed. Rep. 256
"In the time of slavery in the United States white person was generally construed as a person without admixture of colored blood. In various statutes and decisions in different States since 1865 white person is construed as in effect (as of 1913): one not having any negro blood (Ark., Okla.); one having less than one eighth of negro blood (Ala., Fla., Ga., Ind., Ky., Md., Minn., Miss., Mo., N.C., S.C., Tenn., Tex.); one having less than one fourth (Mich., Neb., Ore., Va.); one having less than one half (Ohio). Since the passage of civil rights legislation in the 1960's and 1970's, the term has little legal significance -- for some purposes, as in filling out questionnaires, a person's race is whatever the person claims it to be."
[Webster 1913 Suppl.]