The Gold Rush migration into California was remarkably diverse—somewhere between one-third to half of the 300,000 people who poured into the state in the decade following the discovery at Sutter's Mill were not white American citizens. A visitor to the diggings at the peak of the Gold Rush might have encountered Indians, Californios, African Americans (both slave and free), Chinese, Mexicans, South Americans, Australians, and Europeans working the mines cheek-by-jowl with Anglo migrants from the United States.
At first, all worked their claims in relative equality. However, as the placer gold began to pan out, white Americans sought to limit foreigners' ability to compete for increasingly scarce gold. In 1850 the new California legislature passed a heavy Foreign Miners Tax, demanding that non-citizens pay a prohibitive fee of $20 per month for the right to work their own claims. When the victims of the tax (mainly citizens of Mexico and Chile) refused to pay, Americans organized vigilante mobs to drive them out of the goldfields.
At the same time as white Americans were using legal discrimination and extra-legal violence to consolidate their control over the Sierra gold country, California's Indians were suffering a fearful holocaust. In 1846, the still-Mexican province of Alta California's population was estimated to include 150,000 Indians, 7000 Californios, and fewer than 900 foreigners (mostly Americans). The influx of hundreds of thousands of fortune-seekers resulted in the collapse of California's Indian population, in circumstances historian Richard White has described as "very close to genocide."9 Starvation, disease, and violence combined to reduce California's Indian population by 80% between 1848 and 1860.
The Gold Rush was a multicultural affair, generating unprecedented economic opportunities for enterprising miners from around the world, even as white American Forty-Niners sought to mobilize the privileges of citizenship to monopolize those opportunities for themselves. The Gold Rush thus epitomized, in many ways, the fraught history of race in America.