One of the great conflicts within the labor movement existed between the Craft Unions and the industrial unions. When the American Federation of Labor indicated reluctance to organize unskilled workers, John L. Lewis created the Committee for Industrial Organization within the AFL in 1935. In following year, unwilling to accommodate the CIO`s demands, the AFL expelled the members of the CIO, who organized themselves into the Congress of Industrial Organizations two years later.
Lewis created the Committee for Industrial Organization when he realized that any gains won for miners could be lost if he did not organize such "captive mines" as those held by the steel producers` United States Steel Company, which alone employed 170,000 workers. Because that meant including unskilled as well as skilled workers, many of the craft unions within the AFL opposed the effort to organize mass-production industries. The CIO proved highly successful and within a few years had organized big steel, automobile, rubber, and other major industries. That exacerbated the schism within the AFL, which refused to accept the new unions because they looked down on both industrial workers and industrial unions as unskilled laborers.
Seeing no future for industrial unions within the AFL framework, Lewis withdrew them and created the Congress of Industrial Organizations in 1938, of which he became the first president. At the founding convention, conducted in Pittsburgh, Pennsylvania, from November 14-18, 1938, Lewis acknowledged the efforts of Samuel Gompers in organizing labor at an earlier stage of the American economy, but pointed out the failure of the AFL to organize the masses of workers in the large industrial companies.
At the same time, less than a year before the outbreak of war in Europe, Lewis reminded the financial and business leaders of America that when, as then seemed likely, that America would be drawn into a world conflict, it would be labor, not management and not the owners, who would preserve democracy by their service.
In 1940, in an attempt to use his prestige to sway the presidential outcome, Lewis vowed to resign as CIO president if Franklin Roosevelt was re-elected. Lewis, who was a Republican, had initially supported Roosevelt for his first two terms, but later began to feel Democrat Roosevelt did not support labor unions, and if a Republican candidate were elected with the help of labor votes, the union would be rewarded. Upon fulfilling his promise, the presidency passed to Philip Murray, president of the United Steel Workers. Murray retained his position until his death in 1952. Walter Reuther of the United Auto Workers became the last president of the CIO, prior to its historic merger with the AFL.
Membership in the CIO rose from four million in 1938 to six million in 1945. In 1949 and 1950, the CIO expelled 11 affiliated unions for having communist ties. Although nearly 650,000 members had been in those unions, many rejoined the CIO in unions that had been established as alternatives to the ones that it deemed to be communist dominated.
The distinction between a purely craft union AFL, and the primarily industrial union CIO, blurred over the years. Due to disagreements between factions, the unions in some industries were split into an AFL union and a CIO union. The International Ladies Garment Workers Union (ILGWU) was one of the original CIO unions, but it soon returned to the AFL.
Thus by 1952, the year when the presidents of both the AFL and CIO died, the AFL had nearly half its membership in industrial unions. Over time the urge to merge grew stronger and in 1955, through the efforts of Reuther, the two organizations merged into the AFL-CIO. As of 2005, the federation of the AFL-CIO comprised more than 13 million American workers in 58 member unions, in nearly every sector of the U.S. economy.