"...the tens of thousands of Chinese laborers who had filled San Francisco's docks, Oakland's factories, and Los Angeles' booming oilfields with cheap, easy labor for the three years since the Ingalls Act expired. In the decade 1902-1912, a little under 30,000 - well above the allowed allotment - of Chinese had arrived in the United States, disproportionately in California; in 1913 alone, even before the war started, nearly as many came, and by the end of 1916 over a hundred thousand Chinese, likely an undercount, were making the passage "across the salt" every year.
The White majority in California had never not viewed this state of affairs as an outright invasion; indeed, anxiety over demographic "replacement" in the 1880s had been part of the reasoning behind two failed acts to ban the immigration of the Chinese entirely and were the impetus behind infamous pogroms such as that in 1893 where much of San Francisco's Chinatown was destroyed; William Rosecrans, a retired general who served as a United States Senator from California from 1885-1897, had attempted twice to run for President on a platform almost exclusively on "Chinese exclusion," and had organized a small but determined clique within his Democratic Party around this idea. These "Dragons" had, in the end, failed to effect either the policy demands they had sought beyond the limits of the Ingalls Act or become the node of influence in the California Democratic organization, and had in many ways petered out with Rosecrans' 1898 death.
The Yellow Peril was never far from Californian minds, however, and the explosion of Chinese immigration during the Great American War saw it rear its head again, this time combined with other strands of racial animus with a much broader political base. At the height of Sinophobic mania in the early 1890s, James D. Phelan had been a private citizen working in banking; he would not be elected Mayor of San Francisco (on a pointedly anti-Chinese platform, granted) until 1896 and served three terms before being elected by the California legislature to the office of United States Senator, to Rosecrans' old seat. By 1916, he was thus California's most senior statesman and his campaign against "the Asiatic races" came to typify the time and bore enormous influence. But the difference now was that he was not alone - by the mid-1910s, Sinophobia was not a mere interest of a hard fringe of the Democratic Party in California but a bipartisan obsession, with the state's Liberals equally eager to prove to a swingy, volatile electorate in the Golden State that they could be just as aggressive on the question. It was a fellow San Franciscan, the Jewish Liberal Congressman Julius Kahn, who sponsored a failed law in 1916 to ban all Chinese immigration to the United States entirely, and Phelan and Kahn provided a crucial cross-partisan coalition in Congress, in both houses, to make sure that with their influence with their state's respective partisan delegations the question remained at the forefront of voters' minds.
1916's ugly, racialized campaigns in California and, to a lesser extent, elsewhere on the West Coast revealed also that it was not purely Chinese who drew the ire of the White majority. Pamphlets made lurid descriptions of the various atrocities in India, where the Ghadar Mutiny had erupted nearly two years prior with much of its financing and intellectual underpinning flowing from Indian immigrants in California and Washington, particularly at various universities, with a strong implication that the same awaited the West Coast if Indian immigration was not cut off. The unpopularity of the International Workers of the World was leveraged by campaigns emphasizing the membership of Punjabi migrants and Chinese dockworkers in IWW-associated unions and suggested that "a yellow-brown California is an anarchist California," and Kahn especially leaned into ugliness by accusing socialist-sympathetic immigrants of plotting "the next war - the war from within."
The race-baiting of 1916 did not end there, however. Chinese and Indians made easy targets as they were overwhelmingly male, often cloistered in ethnic enclaves across the West Coast, and both of their countries were engulfed in simmering pan-Asian and anti-European revolutionary sentiment that was known to be partially financed from their communities in the United States. By contrast, Japanese arrived in California and Washington often as family units and quickly established themselves as capable entrepreneurs, shopkeepers, and crucially, farmers - in 1916, as many as 80% of California's truck farmers were Japanese, and Washington had a similar percentage. A wide swath of Californian agricultural land from Stockton to near Sacramento was Japanese-owned, and outside of Seattle much of the Green and White River valleys were dotted with small Japanese homesteads growing all manner of produce and livestock, while much of the east side of Lake Washington was cleared for Japanese-owned strawberry and blueberry farms. The Japanese often converted to Christianity, especially Methodism, and often gave their children Christian first names even as they maintained certain Shinto-inspired traditions from home. While cities like Los Angeles, Oakland and Seattle had distinct "Japantown" districts, the Japanese were known for fanning out and attempting to, at least to an extent unseen by the Chinese, Indians or even Koreans who arrived in somewhat smaller numbers, assimilate.
The local White communities, however, emphatically rejected the idea of Japanese assimilation and immigration, and by 1916 the cause of Japanese exclusion was almost as determined as the longstanding one of China, with the major caveat that the federal government was considerably more keen to get along with ascendant, industrializing Japan, with whom America had always enjoyed fairly decent relations, than with turbulent, corrupt post-revolutionary China. As such, a full ban of Japanese from immigrating to the West Coast would have been disastrous for trans-Pacific relations, and both Democratic and Liberal administrations in the 1910s worked hard to prevent such a bill from occurring. States in response were forced to find their own solutions, and in California Phelan and Kahn joined forces to advocate for the Alien Land Law, which forbade immigrants "ineligible for naturalization" (in other words, all Asian immigrants) [1] from owning land. The fervor with which the public came to approve of this law surprised even Phelan; it passed with massive bipartisan margins in the California state legislature after a flurry of letter writing campaigns despite being at the height of the war, and Governor Hiram Johnson, an early modest skeptic, chose political expediency and signed the law so as to not risk winning a Senate seat in the 1916 general election. [2]
The Alien Land Law of 1916 had obvious loopholes - the ban on post-facto legislation meant that the vast Japanese-owned landholdings could not be retroactively denied to their current owners, and Japanese parents simply "leased" or "registered" their land to American-born nisei children; while the Land Law itself was upheld unanimously in a 1920 Supreme Court case, two years later the same Court struck down an attempt to ban this practice, and the Japanese-American community's path to becoming the wealthiest and most influential Asian-American group was from then on clear. More than anything, it revealed something about American racial attitudes at the time: no matter what a new group did to attempt to assimilate and become "American," in the way that countless Irish, German, Norwegian, Ukrainian, Hungarian and all kinds of other European groups had done in homesteading across the Midwest, they would nonetheless be rejected out of a racial animus that was increasingly setting in across the political and socioeconomic spectrum (the pro-Land Law campaign was financed generously by San Francisco's university-educated, Liberal-voting elite and championed by healthy Democratic majorities in the legislature). And, too, what happened in California became important elsewhere - Washington, Oregon, Nevada, Montana and Idaho would follow the Golden State's lead in 1917-18, where legislators tripped over themselves to pass equally if not more draconian Japanophobic laws intended to make one thing very clear: you are not welcome here."
- The Yellow Peril [3]
[1] True to OTL
[2] Also true to OTL - indeed there he was outright opposed but when it passed with veto-proof majorities he changed his mind and made sure to attach his name to it.
[3] One thing I want to explore is West Coast history specifically. It gets understandably subsumed a bit by the main narrative of the civil rights movement in the United States, but laws targeting Asians in California and neighboring states in OTL were just a rung or two below Jim Crow. And unlike the South where race often translated directly to voting habits, it was pretty bipartisan in terms of how much locals did not want Japanese, Chinese, etc. to have equal rights