Based on the lot description by James Matthews, Senior Numismatist and Consignment Director, U.S. Coins
The discovery of gold at Sutter’s Mill in California in January 1848 caused a dramatic change in the United States and in the history of the U.S. Mint. The large quantities of bullion discovered led in part to the Mint Act of March 3, 1849, which authorized two new gold denominations, the gold dollar and the $20 double eagle. But despite the bonanza of gold coming from California, there was still a shortage of circulating coins in that area. Some private gold coins were being made, but they were not enough. In order to alleviate the situation, in 1850 a United States Assay Office was established in San Francisco, and in December of that year, a few months after California had achieved statehood, President Millard Fillmore recommended that a branch mint be established in the state. On July 3, 1852 the bill became law.