United Mineworkers of America
Mineworkers of America, United (UMW), U.S. labor union for workers in coal mines and coal industries. The UMW is an industrial union, with membership based on an industry rather than on job skills. Founded in 1890, it was a member of the American Federation of Labor (AFL) until 1936 (rejoining briefly 1946–47). Under the leadership of John L. Lewis, union president 1919–60, it then became a moving force in the formation of the Congress of Industrial Organizations (CIO; 1935). It resigned from the CIO in 1942 and is an unaffiliated union.
See also: Unions, labor.