California is a sparsely populated Mexican province, home to about 7,000 Californios (Mexican citizens), 150,000 Indians, and 900 foreigners (mostly Americans).
The sailing ship Brooklyn, carrying 246 Mormon settlers, arrives in San Francisco, which is at this time a tiny Mexican village known as Yerba Buena.
Mormon leader Samuel Brannan opens a general store at Sutter's Fort, near modern-day Sacramento.
James W. Marshall, a foreman building a lumber mill for pioneer landholder John Sutter, discovers gold in the American River east of Sacramento.
California officially becomes United States territory with the signing of the Treaty of Guadalupe Hidalgo, which ends the Mexican-American War by transferring nearly half of Mexico's lands to the United States.
The Californian newspaper in San Francisco reports for the first time on the gold discovery in the Sierra, but most San Franciscans remain skeptical of the report.
San Francisco's California Star newspaper prints a six-page special edition, for distribution in the eastern states, touting "immensely rich" gold mines in California.
San Francisco merchant Samuel Brannan runs through the streets of the city, waving a quinine bottle full of gold while shouting "Gold, gold, gold from the American River!"
Virtually the entire male population of San Francisco leaves the city in a rush to the goldfields.
In the first six weeks following the arrival of gold fever in San Francisco, Samuel Brannan earns $36,000—the equivalent of $750,000 today—in profits from his general store, outfitting miners with picks, pans, and shovels.
More than half the miners in the gold fields in the first months of the Gold Rush are Indians, often brutally exploited by whites.
The New York Herald becomes the first major eastern newspaper to tout the discovery gold in California.
The first gold ship, bearing $500,000 bound for the United States Mint, sails from San Francisco.
President James K. Polk confirms the discovery of gold in California in an address to Congress, touching off a migration of hundreds of thousands of men hopeful of striking it rich in the goldfields.
The first Chinese immigrants arrive in San Francisco.
In California, placer miners earn as much as $20 a day from their diggings.
The New York Herald reports that the discovery of gold in California has "set the public mind almost on the highway to insanity."
More than 30,000 Gold Rushers amass in Missouri, waiting for the prairie to harden enough to allow overland travel by wagon to California.
The first American Gold Rushers to sail for California via Cape Horn arrive in San Francisco.
Ninety thousand migrants, known later as "Forty-Niners," arrive in California during 1849. An estimated two-thirds are white Americans, but the Forty-Niners also include large numbers of Chinese, Chileans, Peruvians, Mexicans, Europeans, and Australians. 97% of the migrants are men.
California delegates assembled in the coastal town of Monterey draft a state constitution, requesting admittance to the Union.
$10 million worth of gold is extracted from California mines in 1849.
$41 million worth of gold is extracted from California mines in 1850.
San Francisco's population, less than 1000 at the time of the gold discovery at Sutter's Mill, is now estimated to exceed 30,000.
In Washington, Congress agrees to the Compromise of 1850, which admits California to the Union as a free (non-slave) state.
When easily harvested placer gold is played out, miners require more technologically-intensive techniques to uncover gold buried deeper underground. The heyday of the independent miner wanes as mines became heavily capitalized, large-scale industrial concerns.
The California legislature passes the Foreign Miners Tax, charging foreign nationals $20 a month for the right to work their claims. The measure is aimed mainly at Chileans and Mexicans, as Anglo miners seek to reduce competition for ever-scarcer placer gold.
Targeted by the Foreign Miners Tax and subject to violence and intimidation at the hands of Anglos, an estimated 15,000 Mexican miners flee the gold region.
$75 million worth of gold is extracted from California mines in 1851.
$81 million worth of gold is extracted from California mines in 1852, an all-time high for the Gold Rush era.
California placer miners' average daily earnings fall by more than two-thirds from their 1848 peak, dropping under $6 a day.
A major crop failure afflicts much of rural China, prompting a major exodus of Chinese migrants to the legendary Gam Saan—"gold mountain"—of California. During 1852, more than 20,000 Chinese arrive in San Francisco. Soon the population of the mining region will be more than one-fifth Chinese.
The California legislature passes a second Foreign Miners Tax, this time targeting Chinese competitors for golden riches.
Edward Matteson, a placer miner frustrated by the ever-decreasing yield in free gold, pioneers the technique of hydraulic mining by fashioning a high-pressure hose to erode a hillside, freeing the gold buried within.
The California Supreme Court ruled that the Chinese, like Indians and blacks, have no right to give evidence in state courts. The ruling means that violence against racial minorities can be committed with virtual impunity, as only the testimony of a white citizen can be used as evidence in court. White miners' attacks on Chinese miners drive many from the goldfields.