Green’s Dictionary of Slang

(US) a derog. term for a black person.

1971		E.E. Landy Underground Dict. (1972).
1983		I.L. Allen Lang. of Ethnic Conflict 45: The Name ‘Negro’ and Its Alterations: chigro (a punning blend of chigger and negro, as a sarcastic allusion to the ‘proper’ name for chiggers, the insects); ’gar (clipped form of niggar, a dialectal pronunciation of nigger).