> We cannot say for certain that that happened in 1918 in Haskell County, but we do know that an influenza outbreak struck in January...The report itself no longer exists, but it stands as the first recorded notice anywhere in the world of unusual influenza activity that year.
And later in the article:
> Although some researchers argue that the 1918 pandemic began elsewhere, in France in 1916 or China and Vietnam in 1917, many other studies indicate a U.S. origin. The Australian immunologist and Nobel laureate Macfarlane Burnet, who spent most of his career studying influenza, concluded the evidence was “strongly suggestive” that the disease started in the United States and spread to France with “the arrival of American troops.” Camp Funston had long been considered as the site where the pandemic started until my historical research, published in 2004, pointed to an earlier outbreak in Haskell County.
The CDC has a variety of history pages [0] about the Spanish Flu. The main one acknowledges that there isn't a "universal consensus" about the virus's origin, but doesn't assert any of the other alternative explanations.
The theories that the Spanish Flu might have actually come from China seem to be more recent. Such as this one in 2014 [1] that found reports from 1917 of Chinese suffering Spanish Flu like symptoms. But his explanation for how the first known case in the West was in Kansas – that thousands of Chinese workers were sent to labor around the world – seems really speculative.
Given that there isn't compelling evidence to think the Spanish Flu started elsewhere outside of Kansas, it is funny how not only did it get the name of "Spanish Flu", but also that Kansas managed to not have a long-lasting reputation for terrible disease, even though the Spanish Flu killed more people than (IIRC) all the other 20th century pandemics combined.
[0] https://www.cdc.gov/flu/pandemic-resources/1918-commemoratio...
[1] https://www.history.com/news/china-epicenter-of-1918-flu-pan...
https://en.wikipedia.org/wiki/Spanish_flu