In the 1840s, Sutter’s Fort became the first stopping-off point for overland Anglo-American emigrants coming to California to build farms and ranches. Though sworn to protect the Mexican province from falling under the control of the growing number of Americans, Sutter recognized that his future wealth and influence lay with these Anglo settlers. With the outbreak of the Mexican War in 1846, he threw his support to the Americans, who emerged victorious in the fall of 1847.
With the war over and California securely in the hands of the United States, Sutter hired the millwright James Marshall to build a sawmill along the South Fork of the American River in January 1848. In order to redirect the flow of water to the mill’s waterwheel, Marshall supervised the excavation of a shallow millrace. On the morning of January 24, 1848, Marshall was looking over the freshly cut millrace when a sparkle of light in the dark earth caught his eye. Looking more closely, Marshall found that much of the millrace was speckled with what appeared to be small flakes of gold, and he rushed to tell Sutter. After an assayer confirmed that the flakes were indeed gold, Sutter quietly set about gathering up as much of the gold as he could, hoping to keep the discovery a secret. However, word soon leaked out and, within months, the largest gold rush in the world had begun.