In 1848, San Francisco was a town of 1,000 people, mostly Mexican American and white merchants. By 1849, the first year of the California Gold Rush, the city boomed to 25,000 people from the eastern United States, Europe, Asia, Africa, and South America. Though the riches found in the state’s rivers and mines eventually amounted to little more than a flash in the pan, the lingering effects of the massive migration known as the California Gold Rush would dramatically alter the political, social, and environmental landscape of California.

Source: National Geographic