William Green was born in Coshocton, Ohio, on 3rd March, 1873. He became a miner and eventually became secretary of the United Mine Workers of America. A member of the Democratic Party he was elected to the Ohio Senate in 1910.

In 1914 Green joined the Executive Council of the American Federation of Labour. In 1921 John L. Lewis, leader of the United Mine Workers of America, failed in his attempt to challenge Samuel Gompers for the presidency of the AFL. When Gompers died in 1924 he was replaced by William Green.

In 1935 John L. Lewis joined with the heads of seven other unions to form the Congress for Industrial Organization (CIO). Lewis became president of this new organization and over the next few years attempted to organize workers in the new mass production industries. This strategy was successful and by 1937 the CIO had more members than the American Federation of Labour.

William Green died on 21st November, 1952.