Butte, Anaconda, and Walkerville supplied much of the copper that helped transform the United States from a collection of small, isolated communities into a cohesive, industrialized nation through telegraph, telephone, and electrical lines. Their industrial landscape, marked by gallows frames and the Anaconda Company smokestack, grew from hazardous mining and smelting work that fostered strong worker solidarity. Butte and Walkerville, known as “The Gibraltar of Unionism,” gave rise to two of the nation’s most radical unions, the Western Federation of Miners and the Industrial Workers of the World, whose opposition to “wage slavery” challenged American capitalism. Conflict between labor and capitalism defined the district, especially after the 1917 Butte Granite Mountain/Speculator Mine fire, the nation’s worst hard-rock mining disaster, which was followed by labor unrest and years of martial law in Butte, while Anaconda saw the Company fire suspected Socialists and agitators and devastate the unions. During the New Deal, workers in Butte and Anaconda reorganized after the federal government guaranteed the right to unionize, and their four-month industry-wide strike in 1934 helped precipitate the birth of the CIO and rejuvenate the labor movement nationwide. In 2006, the area’s importance to the intertwined histories of mining and labor was recognized when Butte, Anaconda, and Walkerville were designated a National Historic Landmark, the largest in the West, covering the years 1876-1934 across nearly 10,000 acres with more than 6,000 contributing resources.