Born in Glasgow in 1903 and moved to Seattle (USA) at the age of ten, John Williamson joined the Socialist Labor Party of America in 1918 and played an important role in the struggles of the automobile, steel and electrical workers, and of the unemployed during the Great Depression of the 1930s.

According to the MML Quarterly Bulletin, Williamson was "seeking for the basic causes that made such struggles necessary". In 1921 he decided to join the Communist Party of the United States of America (CPUSA), which managed to survive despite the hostility of the American administration.