The Western Federation of Miners (WFM) was a radical labor union that gained a reputation for militancy in the mines of the western United States and British Columbia. Its efforts to organize both hard rock miners and smelter workers brought it into sharp conflicts – and often pitched battles – with both employers and governmental authorities. One of the most dramatic of these struggles occurred in the Cripple Creek district in 1903–04, and has been called theColorado Labor Wars. The WFM also played a key role in the founding of the Industrial Workers of the World in 1905, but left that organization several years later.
The WFM changed its name to theInternational Union of Mine, Mill, and Smelter Workers (more familiarly referred to as Mine Mill) in 1916. After a period of decline it revived in the early days of the New Deal and helped found the Congress of Industrial Organizations (CIO) in 1935. The Mine Mill union was expelled from the CIO in 1950 during the post-war red scare for refusing to shed its communist leadership. After spending years fighting off efforts by theUnited Steelworkers of America (USWA) to raid its membership, Mine Mill and the USWA merged in 1967.