On April 19, 1920, the Industrial Workers of the World (IWW) and the Metal Mine Workers Industrial Union called for a strike in the mines around Butte. They hoped the strike would help secure higher wages, an eight-hour day, and end the use of the rustling card, a system that allowed employers to blacklist employees involved in union organizing, among other goals. The strike came at a weak point for the union movement in Butte. World War I had undermined the power of the Butte Miners Union and the mines around the town were open shops. Only six years earlier, in 1914, the Butte Miners Union Hall had been destroyed. Rising copper prices, fatal mining accidents, and recruitment by the IWW had further exacerbated tensions in the town. Three years before the strike, an IWW organizer named Frank Little was beaten and hanged from a railroad trestle by unknown assailants. Thus, the strike began in an atmosphere of tension.