Two events offered wealthy Chinese a chance to clean up San Francisco's Chinatown. In 1909 San Francisco decided to celebrate the 140th anniversary of Portola's discovery of the Bay with a six-day Portola Festival; in reality an event to celebrate the reconstruction of San Francisco after the earthquake and the fire. Chinatown made the best of it, presenting itself as a tourist attraction for the first time. Then in December 1915 a world's fair was held in San Francisco to celebrate the completion of the Panama Canal: the Panama-Pacific International Exposition. A telephone line was installed with New York. Philadelphia sent the "Liberty Bell". Spectacular architecture (planned by a committee presided by Willis Polk) dotted the shore, including the Palace of Fine Arts designed by architect Bernard Maybeck (rebuilt in the 1960s, it is the only surviving structure), and the largest wooden-frame huilding in the world, the Machinery Palace, plus replicas of the Panama Canal, of thre Grand Canyon and of Yellowstone Park. Nearly 19 million people from all over the world attended. There was also a "Joy Zone", one of the largest amusement parks ever built, which included a "Chinese Village", whose main attraction was "Underground Chinatown", a grotesque, exaggerated depiction of the underworld of Chinatown, in particular its opium dens. While racist and insulting, this "thrilling" representation of Chinese life meant that Chinatown was becoming a tourist attraction. More importantly, it was "the" deviant aspect of San Francisco, which was otherwise trying too hard to present itself as an ordinary city. What stood out from this exhibition was that the "melting pot" of the USA was mostly a "white" melting pot but in San Francisco it was actually a confluence of white and "yellow".

In August 1915 the Pacific Mail S.S. Company announced that it would cease operations between China and California. Its ships had been the main mode of transportation for the Chinese community. Fearing that Japan (an emerging power after winning the war against Russia in 1905) would now control all the trans-Pacific traffic, Chinese merchants got together and formed the China Mail S. S. Company.

Many of the Chinese immigrants in the first half of the 20th century were self-employed business owners for the simple reason that they couldn't find employment due to the Chinese Exclusion Act. No surprise that they started hundreds of laundries and restaurants. It was obvious to any white observer that these Chinese were simply hard-working honest people, clearly very good at saving money, but the discrimination continued unabated.

Despite these attempts by the "Oriental" groups to gain legitimacy and respect, in 1917 the USA expanded "exclusion" to the whole of Asia (the "Asiatic Barred Zone Act"): Middle East, Central Asia, British India, Indochina, etc. The only exception was the Philippines, which the USA had conquered in the Spanish–American War of 1898: Filipinos were US nationals until 1934, when they were granted independence (actual independence only came in 1945). The Chinese and the Japanese were still able to immigrate into Hawaii because Hawaii was not a state of the USA (just a protectorate) until 1959. Several Chinese and Japanese tried to challenge these laws in courts, but in 1922 the Supreme Court ruled that Japanese-born people were not "white", which meant that, according to the Naturalization Act of 1790, they could not become US citizens, and in 1923 the Supreme Court ruled that Indians too did not qualify as "white". Wong Kim Ark's lawsuit of 1898 had clarified that everybody born in the USA was a citizen but foreign-born Asians were still excluded from citizenship.

In 1911, China’s last emperor abdicated and the Republic of China was established by Sun Yat-Sen, just after Sun had visited San Francisco during his exile. The USA immediately recognized the new government. In 1912 San Francisco's Chinatown elected their own representative (Kuang Yaojie, president of the Ningyang huiguan) to the national congress in China. A few years later the excitement turned into anxiety when in November 1914, during World War I, Japan, allied with Britain and France, first conquered the Chinese port of Qingdao from Germany, and when, in January 1915, Japan issued the "Twenty-one Demands" which basically amounted to China becoming a Japanese protectorate (Japan had already conquered Taiwan from China during the Jiawu Zhanzheng of 1894-95). In 1913 the young Chinese Republic descended into chaos, as Sun Yatsen’s Kuomintang party won elections but China disintegrated in the hands of regional warlords. Mongolia (1911), Tibet (1913) and seven provincial governments declared independence. China entered World War I in 1917 on the side of Britain and the USA, but was betrayed by them at the end of the war and in 1919 students protested in Beijing's Tiananmen Square the decision to grant German-controlled Shandong to Japan, and thus a new nationalist Chinese movement, known as the "May Fourth Movement", was created. The immigrants were increasingly touched by events in the motherland. At this time a number of schools for Chinese children were established, mainly in San Francisco and Hawaii, and mostly sponsored by the benevolent associations. The biggest was the Zhonghua School. These schools typically taught both the Cantonese language and Chinese classics. The Chinese communities also doubled efforts to reshape their image by fighting vices like gambling and prostitution and the tongs.

The Chinese were not allowed to own land but could lease it from white landowners. When in October 1915 a fire destroyed the 100-people Chinatown of Walnut Grove, south of Sacramento, a group of Chinese led by businessman Lee "Charlie" Bing (who had owned a gambling house, a hardware store, a grocery store, a barber shop, a pool hall and a herbal medicine store) leased land from a man called George Locke and built their own town, Locke. It was the first town in California built by the Chinese for the Chinese. More Chinese workers came, employed in the farms and canneries of the Delta region. It became famous among white people because of its (illegal) casinos (like the building that today hosts the Dai Loy Museum).

In 1919 Chen Chunrong, a lawyer who had worked for the Italian American Bank (today's Bank of America), launched the joint-stock Chinese American Agricultural Company to purchase a large farm near Stockton. Hundreds of Chinese invested in it.

There were still tong wars in the first twenty years of the new century, and they often spread to many cities. One started in 1917 in Portland and one in 1921 in Butte, north of Sacramento. But those were the last ones.

In 1919 the USA ratified the 18th Amendment to the Constitution, which prohibited "the manufacture, sale, or transportation of intoxicating liquors" and then passed the "National Prohibition Act". Nightclubs serving alcohol illegally popped up in Chinatown.

The Chinese population of San Francisco was confined to a few blocks of the city. The Chinese dared not cross California Street or Broadway, because on the other side it was "white" territory, and those Chinese who entered it risked being attacked.