Claim: San Francisco is in the United States.

The California Gold Rush -LRB- 1848 -- 1855 -RRB- began on January 24 , 1848 , when gold was found by James W. Marshall at Sutter 's Mill in Coloma , California . The news of gold brought some 300,000 people to California from the rest of the United States and abroad . The sudden influx of immigration and gold into the money supply reinvigorated the American economy , and California became one of the few American states to go directly to statehood , in the Compromise of 1850 . The Gold Rush initiated the California Genocide , with 100,000 Native Californians dying between 1848 and 1868 . By the time it ended , California had gone from a thinly populated ex-Mexican territory to the home state of the first nominee for the Republican Party .   The effects of the Gold Rush were substantial . Whole indigenous societies were attacked and pushed off their lands by the gold-seekers , called `` forty-niners '' -LRB- referring to 1849 -RRB- . The first to hear confirmed information of the gold rush were the people in Oregon , the Sandwich Islands -LRB- Hawaii -RRB- , and Latin America , and they were the first to start flocking to the state in late 1848 . Of the 300,000 people who came to America during the Gold Rush , approximately half arrived by sea and half came overland on the California Trail and the Gila River trail ; forty-niners often faced substantial hardships on the trip . While most of the newly arrived were Americans , the Gold Rush attracted tens of thousands from Latin America , Europe , Australia , and China . Agriculture and ranching expanded throughout the state to meet the needs of the settlers . San Francisco grew from a small settlement of about 200 residents in 1846 to a boomtown of about 36,000 by 1852 . Roads , churches , schools and other towns were built throughout California . In 1849 a state constitution was written . The new constitution was adopted by referendum vote , and the future state 's interim first governor and legislature were chosen . In September , 1850 , California became a state .   At the beginning of the Gold Rush , there was no law regarding property rights in the goldfields and a system of `` staking claims '' was developed . Prospectors retrieved the gold from streams and riverbeds using simple techniques , such as panning . Although the mining caused environmental harm , more sophisticated methods of gold recovery were developed and later adopted around the world . New methods of transportation developed as steamships came into regular service . By 1869 railroads were built across the country from California to the eastern United States . At its peak , technological advances reached a point where significant financing was required , increasing the proportion of gold companies to individual miners . Gold worth tens of billions of today 's dollars was recovered , which led to great wealth for a few . However , many returned home with little more than they had started with .