News that large quantities of gold had been found in California soon spread around the globe. By summertime, rumors were flying that prospectors had already found thousands of dollars worth of gold.
By confirming those rumors in December 1848, U.S. President James K. Polk effectively made the California Gold Rush official. Between 1848 and 1858, more than 300,000 people arrived in California to seek their fortunes. Most of them arrived in 1849, which earned them the nickname “forty-niners.” The Gold Rush became the largest migration, or mass movement of people, in U.S. history.