Cox moved to San Francisco in 1953 at age 17. He became interested in political action by following the events of the Civil Rights Movement during the next several years. Cox was deeply disturbed by events such as the 16th Street Baptist Church bombing, in which 4 little black girls were killed and a further 22 people injured in an act of White Supremacist terrorism carried out by the Ku Klux Klan. He was also influenced by the writings of W.E.B. Du Bois and Herbert Aptheker, introduced to him by a white communist friend, Mark Hanson. He became affiliated with the Congress of Racial Equality, and in 1964 and 1965 he was involved in the series of protests directed against the Bank of America, San Francisco hotels, rental agencies and the automobile industry, who were discriminating against African-Americans.