International Union of Mine, Mill, and Smelter Workers

The International Union of Mine, Mill, and Smelter Workers (IUMMSW) emerged in 1916 from the more radical Western Federation of Miners (WFM) which organized mine and copper industry workers. IUMMSW reasserted its presence in the western mines, most successfully during the five-month strike in Butte and Anaconda (Montana) in 1934. A founding member of the Congress of Industrial Organizations (CIO), the IUMMSW was expelled in 1950 because of the Union's perceived Communist ties. In 1967, the IUMMSW merged with the United Steelworkers of America after considerable raiding of union locals by the anticommunist USWA.

From the description of International Union of Mine, Mill, and Smelter Workers records, 1946-1982 (bulk 1946-1967) (Pennsylvania State University Libraries). WorldCat record id: 465191404