The discovery of gold in California in 1848 had set this mining frenzy in motion. Over the next thirty years, successive waves of gold and silver strikes in Colorado, Nevada, Washington, Idaho, Montana, and the Dakotas lured individual prospectors with shovels and wash pans. One of the biggest finds came with the Comstock Lode in the Sierra Nevada. All told, miners extracted around $350 million worth of silver from this source. One of those who came to try to share in the wealth was Samuel Clemens. Like most of his fellow miners, Clemens did not find his fortune in Nevada and soon turned his attention to writing, finally achieving success as the author called Mark Twain.

Like Twain, many of those who flocked to the Comstock Lode and other mining frontiers were men. Nearly half were foreign-born, many of them coming from Mexico or China. Using pans and shovels, prospectors could find only the ore that lay near the surface of the earth and water. Once these initial discoveries were played out, individual prospectors could not afford to buy the equipment needed to dig out the vast deposits of gold and silver buried deep in the earth. As a result, western mining operations became big businesses run by men with the financial resources necessary to purchase industrial mining equipment.

When mining became an industry, prospectors became wageworkers. In Virginia City, Nevada, miners labored for $4 a day, an amount that barely covered the expenses of life in a mining boomtown. Moreover, the work was extremely dangerous. Mine shafts extended down more than a thousand feet, and working temperatures regularly exceeded 100 degrees Fahrenheit. Noxious fumes, fires, and floods of scalding water flowed through the shafts, and other threats killed or disabled thousands each year.

Struggling with low pay and dangerous work, western miners sought to organize. In the mid-1860s, unions formed in the Comstock Lode areas of Virginia City and Gold Hill, Nevada. Although these unions had some success, they also provoked a violent backlash from mining companies determined to resist union demands. Companies hired private police forces to help break strikes. Such forces were often assisted by state militias deployed by elected officials with close ties to the companies. For example, in 1892 the governor of Idaho crushed an unruly strike by calling up the National Guard, a confrontation that resulted in the deaths of seven strikers. A year later, mine workers formed one of the most militant labor organizations in the nation, the Western Federation of Miners. Within a decade, it had attracted fifty thousand members, though membership did not extend to all ethnicities. The union excluded Chinese, Mexican, and Indian workers from its ranks.