From The Other Slavery: The Uncovered Story of Indian Enslavement in America, by Andrés Reséndez (HarperCollins, 2016), Kindle pp. 102-103:
THE CALIFORNIA GOLD rush transformed the western United States. Within one decade of James W. Marshall’s discovery of a few flecks of gold in a ditch in 1848, some three hundred thousand migrants had moved to California. These Chinese, Italian, German, Chilean, and other newcomers turned the remote and picturesque Mexican outpost of San Francisco into a bustling port. They also fanned out into the Sierra Nevada to build cabins, divert rivers, and pan for the yellow metal. This is a familiar story of long journeys, ethnic conflict, broken dreams, and explosive growth.
Yet the California gold rush was neither the largest metal-induced rush of North America nor the most transformative. By any measure, that title belongs to the earlier Mexican silver boom. In terms of duration, for instance, the California gold rush was like a hurricane. Gold production skyrocketed in 1849 but peaked as early as 1852, only four years after the start of the rush, and declined markedly thereafter. For all practical purposes, the rush was over by 1865, lasting less than twenty years. The use of pressurized water to wash down entire hillsides—a process known as hydraulic mining—kept gold production from declining even faster than it did. By contrast, Mexico’s silver boom started in the 1520s and grew through the sixteenth and early seventeenth centuries, reaching a plateau at the end of this period. Remarkably, it gained a second wind in the late seventeenth century and kept increasing during the eighteenth century, not attaining its high-water mark until the first decade of the nineteenth century—almost three centuries after the boom had begun. By then silver was the principal way in which empires and nations around the world stored their wealth, and the Spanish peso had emerged as the first global currency, used throughout the Americas, Europe, and Asia, where it was often countersigned (authenticated by the treasury or other monetary authorities) and employed in everyday transactions. It remained legal tender in the United States until 1856.
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Not only did the Mexican silver boom last longer than the California gold rush, but it was more extensive. The gold rush was confined largely to the northeastern quadrant of the state, with a few additional mines sprinkled along its border with Oregon and in southern California. Prior to the gold rush, there had been small strikes in the southern Appalachians (North Carolina, South Carolina, Tennessee, and Georgia), and after the California discoveries, new goldfields emerged in some of the Rocky Mountain territories. Mexico’s centuries-long silver boom surpassed these gold strikes in both geographic scope and sheer density. Historians usually refer to the mines of northern Mexico, but in truth the silver boom started in southern and central Mexico. Present-day tourists driving from Mexico City to Acapulco still stop at Taxco (1534), a silver town that Hernán Cortés himself developed. Taxco was part of a cluster of mines in southern Mexico that included Sultepec (1530), Amatepec (1531), Zacualpan (circa 1540), Zumpango (1531), and others. Only gradually did prospectors venture north into the lands of the Chichimecs, along the Pacific coast and up into the escarpments of the Sierra Madre Occidental. They had to bring in Indians from central Mexico as workers and overcome other tremendous logistical problems, but they succeeded in establishing a string of mines throughout western Mexico. After this initial push, prospectors crossed the Sierra Madre, proceeding on to the central plateau, where they founded some of the richest mines in the world, including Zacatecas (1546) and Guanajuato (1548). But even these mines were not sufficient. Spaniards next explored the present-day states of Durango and Chihuahua, as well as parts of northeastern Mexico. Altogether, they founded more than 400 mines (143 in the sixteenth century, 65 in the seventeenth century, and 225 in the eighteenth century) scattered throughout much of Mexico, from the semitropical regions of the south to the deserts of Chihuahua, and from the Pacific to the Atlantic coast.
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Given its longer duration and more extensive geography, it is no wonder that Mexico’s silver boom produced roughly twelve times as much metal as the nineteenth-century gold rushes in the United States—44.2 million kilograms (48,722 tons) of silver compared with 3.7 million kilograms (4,078 tons) of gold (see appendix 4). This massive production is even more impressive considering the work and danger involved. The gold of California lay in placers, or surface deposits of sand and gravel, which had resulted from mountains eroding and yielding nuggets or flecks of gold, which collected at lower elevations along hillsides and in streams. Mining these bits of precious metal required a great deal of superficial digging, carrying, and washing. As we saw earlier in the Caribbean, that could be very hard work, but it was not nearly as daunting or dangerous as mining silver. Instead of lying in open-air deposits, the silver had to be extracted from deep underground. The main shaft in the mines of San Luis Potosí was 250 yards long, and that in the Valenciana mine in Guanajuato plunged 635 yards down. When this shaft was completed around 1810, it was considered the deepest man-made shaft in the world. Digging to such depths required an untold amount of work, and yet this was only the beginning of a long, involved process that required bringing the ore to the surface (frequently on the backs of humans), crushing the rocks into a fine powder, and mixing that powder with toxic substances such as lead and mercury.
If the silver boom had occurred in the nineteenth century, Mexico would have become a worldwide magnet, like California. In an era of newspapers, steamboats, and widespread transoceanic travel, there is little doubt that the great Mexican silver mines would have lured immigrants from all quarters of the globe. But because the boom predated these communication and transportation conveniences and unfolded at a time when the Spanish monarchy prohibited all foreigners from going to the silver districts, Mexico had to make do with its own human resources. Whereas California attracted three hundred thousand people, colonial Mexico had to satisfy a hugely greater labor demand with no access to volunteers from the rest of the world.
