When did the California Gold Rush officially begin?

The California Gold Rush officially began in 1848 following the discovery of gold at Sutter's Mill near Coloma. This pivotal event is significant in American history as it prompted a massive influx of people to California in search of wealth, drastically transforming the state's demographics, economy, and infrastructure. The year 1848 marks the start of a period where thousands, often referred to as "Forty-Niners," migrated to California, leading to its rapid growth and eventual admission as the 31st state in 1850. The other years listed—1840, 1855, and 1862—are not associated with the initial discovery of gold or the peak of the Gold Rush, thus making 1848 the correct answer.