Congress of Industrial Organizations

The Congress of Industrial Organizations, or CIO, proposed by John L. Lewis in 1938, was a federation of unions that organized workers in industrial unions in the United States and Canada from 1935 to 1955. The Taft-Hartley Act of 1947 required union leaders to swear that they were not Communists. Many CIO leaders refused to obey that requirement, later found unconstitutional. The CIO merged with the American Federation of Labor to form the AFL-CIO in 1955.

The CIO supported Franklin D. Roosevelt and the New Deal Coalition, and was open to African Americans. Both federations grew rapidly during the Great Depression. The rivalry for dominance was bitter and sometimes violent. The CIO (Committee for Industrial Organization) was founded on November 9, 1935, by eight international unions belonging to the American Federation of Labor.

In its statement of purpose, the CIO said it had formed to encourage the AFL to organize workers in mass production industries along industrial union lines. The CIO failed to change AFL policy from within. On September 10, 1936, the AFL suspended all 10 CIO unions (two more had joined in the previous year). In 1938, these unions formed the Congress of Industrial Organizations as a rival labor federation. In 1955, the CIO rejoined the AFL, forming the new entity known as the American Federation of Labor-Congress of Industrial Organizations (AFL-CIO).