Congress of Industrial Organizations
The Congress of Industrial Organizations was a federation of industrial unions in the United States and Canada from 1935 to 1955. John L. Lewis proposed the idea of the CIO in 1932. The Taft-Hartley Act of 1947 required union leaders to swear that they were not Communists and several CIO leaders refused to obey that requirement, which was eventually found unconstitutional. The CIO merged with the American Federation of Labor to form the AFL-CIO in 1955.