In 1848 there were only 325 Chinese in the whole of the USA. There were probably only about 50 Chinese in the whole of California before 1848 and only seven arrived in San Francisco in 1848. The first known Chinese woman to arrive in San Francisco was a maid, known as Marie Seise, who worked in Hong Kong for the family of US merchant Charles Van Megen Gillespie (possibly the first US merchant to reside in the British colony of Hong Kong) and moved to San Francisco with them in February 1848, just before the Gold Rush. A maid had also been the first Chinese woman to immigrate to New York: Afong Moy in 1834, raised in Guangzhou. But some Chinese learned of the California gold much earlier than US citizens east of the Sierra Nevada: the trip to China took only three months, therefore news reached China faster than it did New York or Boston. In late December a ship arrived in Hong Kong carrying some gold dust from California and a copy of a Honolulu newspaper writing about the gold in California. In January 1849, Hong Kong’s English-language weekly, Friend of China, reprinted the article. The news spread in Guangdong province. Men had been leaving the Pearl River Delta since the 1830s, often for South America and the Caribbeans, often as indentured laborers drafted against their will in the so-called "coolie trade”.

The first people to rush to California were actually US citizens living in Hong Kong (at the time a British colony), notably Yuan Sheng, a Chinese who had become a US citizen earlier in South Carolina and called himself Norman Assing. Assing landed in July. Already a prominent merchant, he opened both a restaurant and a brothel, and in December founded the Chew Yick Association, one of the earliest organizations to help Chinese immigrants. The Kong Chow association instead helped immigrants from the Sun Wui and Hawk Shan districts. Tong Achick, who arrived in 1851 already fluent in English, became a rich merchant and founded the Yeong Wo association for immigrants from his native district of Heung Shan. At the time many Chinese suffered from civil unrest and famine. The motivation to emigrate was great, and California was being depicted in Cantonese as "Gam San" (“Gold Mountain”). For most of China the rest of the world was a distant and mysterious land, but the people of the Pearl River Delta were instead used to Westerners because of Canton (Guangzhou) being the only official trading port for Westerners, a stop for many US merchants and missionaries, and because of Hong Kong, that had just become a British colony in 1842. The first Chinese immigrants came mostly from the district speaking Hoisanese, a dialect of Cantonese. Most of them didn't know any English, and would take any job, but there were plenty of humble jobs for those willing to take them. One of the fastest growing districts in San Francisco was the old Yerba Buena area, which was now the preferred location of Chinese businesses: it soon became better known as Chinatown.

In October 1849 a group of 50 or 60 Chinese arrived under contract with an English businessman of Shanghai and were sent to a camp in the gold region. That pioneered the system of "huiguans", merchant companies based in San Francisco that found jobs for groups of laborers. They hired the laborers in China, organized sea passages for them, and delivered them to the California contractors: the Kong Chow company was formed in 1850, the Sze Yup company and the Sam Yup company in 1851, and by 1854 there were four, known as the "Four Great Houses", each one representing a different district and dialect of the Pearl River Delta (later there were six, that merged in 1862 in what would become the Chinese Consolidated Benevolent Association).

Their leaders were the relatively wealthy and educated Chinese who had arrived earlier, for example Yee Ah Tye, who had arrived in San Francisco in 1847 and become Sze Yup's leader. Only 325 Chinese arrived in San Francisco in 1849, and only 450 in 1850, but in 1851 the number jumped to 2700 and in 1852 it skyrocketed to more than 20,000. The Chinese immigrants were almost all men. In 1850 there were more than four thousand Chinese men in San Francisco but only seven Chinese women. The vast majority of the female Chinese population was employed in the brothels that rapidly multiplied during the Gold Rush, like the famous ones (more than one) owned by the Cantonese madam Ah Toy (who claimed to have been the first prostitute of San Francisco). The girls had mostly been sold by their families back in China and their status in San Francisco was basically that of indentured slave girls. Both merchants and criminal gangs imported unmarried Chinese women for the needs of the vast male unmarried population. Lai Chu-chuen opened the first Chinese bazaar in 1850. The first troupe from China to perform Chinese opera arrived in 1852 and within 20 years at least four theaters were built, including the Donn Quai Yuen (Grand Chinese Theatre). The Chinese immigrants started building their own temples, such as, in 1851, the Tien Hou Temple, a Taoist shrine to the divine protector of seafarers. Most Chinese immigrants were Taoists.

While we tend to focus on the poverty that induced many Chinese to flee their country, it is also important to understand the opposite motivation: the Pearl River Delta, a relatively wealthy (not poor) region, was home to a vibrant market and export economy, its merchants were eager to find new markets, and their workers were eager to find virgin places where to emulate those merchants. One motivation was to escape chaos and poverty, but the other one was the belief that they could transplant their industrial and commercial skills in the virgin continent. Early Chinese immigrants came from the Pearl River Delta not because it was the poorest region but because it was the most familiar with Western ideas and manners, thanks to the missionaries who had established hospitals and schools, thanks to merchants like Wu Bingjian (aka Houqua) who had mastered the international trade, and thanks to popular books like Lin Zexu's "Sizhou Zhi/ Gazetteer of the Four Continents" (1839) and Xu Jiyu’s "Yinghuan Zhilue/ Brief Record of the Ocean Circuit" (1848). In 1850 a ship from Hong Kong delivered 50 Chinese immigrants but also more than one thousand pieces of furniture and more than one thousand blocks of granite. We tend to emphasize the number of Chinese who immigrated and to ignore the ones who left: it is true that between 1848 to 1876 more than 200,000 Chinese arrived in San Francisco, but it is also true that in the same period more than 93,000 left.

Not all Chinese headed for the gold mines. The Monterey peninsula boasted four Chinese fishing villages between Point Lobos and McAbee Beach. The first Chinese arrived in the 1850s from China, landing near today's Pt Lobos State Park. Others were, quite simply, shipwrecked on that coast. At one point Point Alones (in today's Pacific Grove) had more Chinese than San Francisco's Chinatown.

Chinese from a village called Lee Ook Bin of Guangdong province, led by John Sing Lee, tried to sail to Monterey but instead landed in 1852 at Casper Beach, near Mendocino, a center of logging. They found employment in the lumbermills and also built a Taoist temple that is still standing (known as both Mo-dai Miu and Temple of Kuan Tai). One can argue that the Chinese were not so much coming to America as escaping China. After losing the Opium War to England in 1842, China lost a second Opium War (the "Arrow War") to England and France in 1856. Meanwhile the Taiping Rebellion of 1851-64 resulted in the death of about ten million people. The Guangdong province was also devastated by an ethnic conflict between the majority Punti (Cantonese) people and the minority Hakka people from 1855 until 1867. By 1859 about 10% of California’s population was born in China.