1932 (as an adjective from 1938), from race (n.2) + -ist. Racism is in continual use from 1936 (from French racisme, 1935), originally in the context of Nazi theories. These words replaced earlier racialism (1882) and racialist (1910), both often used early 20c. in a British or South African context. There are isolated uses of racism from c. 1900.
In the U.S., race hatred, race prejudice had been used, and, especially in 19c. political contexts, negrophobia. Anglo-Saxonism as "belief in the superiority of the English race" had been used (disparagingly) from 1860. Anti-Negro (adj.) is attested in British and American English from 1819.