On February 2, 1848, the American-Mexican War ended with the signing of a treaty that left California in the hands of the United States. Eight days before, carpenter James Marshall had found flakes of gold in the American River in the Sierra Nevada mountains while building a sawmill of John A. Sutter, who owned a ranch in Sacramento Valley. To test if it was gold, Marshall tried to break the nugget between two rocks - only to find out that it could change shape, but not broken. He was sure that what he had discovered, was gold.
Marshall and Sutter tried to keep the discovery for themselves, but Mid-March, a San Francisco newspaper published an article reporting that gold had been found at Sutter's Mill. Within two weeks, the paper's staff had left to go to Sutter's creek. They were soon followed by about 75% of the male San Francisco population, who turned their backs on their fields and labors in the expectancy of making quick fortune with finding gold. By August, some 4,000 miners had reached the area.
The news soon spread worldwide, and by 1849, 80,000 men from the Americas, Britain, Australia, Europe and China arrived in California by ship or by the Californian trail. The would-be gold-miners migrating were called "forty-niners". The California population rose to over 200,000 in less than three years. Few women accompanied their husbands in the early years, and they took on the responsibility of running farms and businesses.