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In 1900, the Bubonic Plague Struck San Francisco

This infectious disease isn't just a relic of the medieval era.

bubonic plague san francisco
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  • Marine Hospital Service workers tying tags on rats in San Francisco, c. 1907–1909.Photo Credit: U.S. National Library of Medicine via Science History Institute

When most of us think of the bubonic plague, we think of the infamous Black Death that killed as much as half of the total population of Europe in the 14th century. But the bubonic plague was not eradicated when the Black Death pandemic came to an end. In 1855 another outbreak of the plague began, killing more than 12 million people in India and China and spreading to every corner of the world. 

In 1900, it reached San Francisco. In fact, there’s reason to believe that it may have arrived well before then, but the first cases weren't confirmed until 1900. By then, the plague was already raging in countries all over the world, with as many as 10 million dead in India alone. In 1894, the plague had reached Hong Kong, where it killed over 6,000 people in six months and led to a massive exodus from the city.

Related: How the Black Death Led to the Peasants' Revolt

Because Hong Kong was a major maritime shipping hub, the plague was able to spread from there to many other points in the world, though the exact origin of the plague that reached the harbors of San Francisco remains unknown. Before the plague made its way to San Francisco, it hit the Territory of Hawaii, which had just been annexed by the United States government in 1898.

By 1899, the plague had arrived in Honolulu, with residents reporting all the usual symptoms of bubonic plague, including swollen lymph nodes which formed buboes and eventually led to organ damage and death. Unsure how to combat the disease, officials took to burning infected houses, which produced an out-of-control conflagration that burned nearly all of Honolulu’s Chinatown, leaving some 6,000 people without homes.

Unfortunately, it was far from the last time that Chinese immigrants would come under (sometimes literal) fire for the spread of the plague. By 1900, all ships coming into San Francisco were rigorously inspected for signs of plague. However, inspectors were searching for signs of the disease in passengers, not for vectors that might be carrying it, such as rats and fleas. As such, the plague was able to make its way past authorities and into San Francisco, where it quickly spread through Chinatown.

At the time, racial animosity toward Chinese immigrants was widespread, and many landlords refused to upkeep and maintain their own property when renting to Chinese tenants, forcing many inhabitants of Chinatown to live in squalid conditions that exacerbated the spread of the disease. Nor were the racist housing policies the only time that Chinese individuals would be targeted during the outbreak.

bubonic plague 1900
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  • A fire set by public health officials burns in Honolulu’s Chinatown.

    Photo Credit: Chaminade University of Honolulu via Science History Institute

Immediately following the first death associated with the plague, the San Francisco Health Board placed all of Chinatown under quarantine without any notice. The quarantine only applied to ethnically Chinese residents. White people could still leave and pass through the area, but Chinese residents could not. What’s more, doctors were barred from entering the quarantine zone in order to provide effective medical aid.

While the first quarantine was dropped within days due to massive public backlash and a lack of immediate evidence that plague had been the victims' cause of death, it was followed by a number of other racist policies that targeted Chinese immigrants, who San Francisco mayor James D. Phelan called “a constant menace to the public health”. These policies included confiscating and burning property that was suspected to “harbor filth.”

Related: Explore History's Deadliest Diseases

Though the steps taken against the city’s Chinese population were often extreme, the reaction to the presence of the plague was, itself, a mixed bag. Individuals such as Joseph J. Kinyoun, the chief quarantine officer of the Marine Hospital Service, and U.S. Surgeon General Walter Wyman were deeply concerned about the spread of the plague into the rest of California and the United States at large. However, they faced stiff opposition from California governor Henry Gage. Gage saw awareness of the plague as a danger to the economy of the city and the state and went to extraordinary lengths to suppress any evidence of the outbreak, including denying federal authorities access to the University of California’s labs at Berkeley by threatening to cut off the school’s funding.

Nor was Gage the only one stringently resisting efforts to acknowledge the plague. Before the first confirmed case of the bubonic plague had even reached the city, Kinyoun had ordered all ships coming to San Francisco from places with known outbreaks to fly yellow flags to warn of possible plague. Many ship owners and entrepreneurs resisted the order, arguing that it was bad for business and “unfair to ships that were free of plague.”

Meanwhile, others cited a wide array of dubious claims to argue that there was no way the plague could take hold in San Francisco, such as a February 4th article in the San Francisco Examiner—which was published just days before the first confirmed outbreak in the city—with the headline, “Why San Francisco is Plague-Proof.” One argument put forward was that white people could not get the plague because “Europeans eat meat,” which has…many problems on its face, not the least of which is the glaring European death toll of the previous bubonic plague outbreak.

Related: Bacteria and Bayonets: How Disease Has Impacted American Warfare

Governor Gage’s political efforts to discredit Kinyoun and Wyman—among others—only ramped up as the San Francisco outbreak grew worse. Supported by railroads and city business interests, as well as several sympathetic newspapers, Gage waged a defamation campaign against Kinyoun, accusing him of injecting plague bacteria into cadavers who had already died of other causes in order to falsify evidence. He also allocated more than $100,000 toward a public campaign to deny the existence of the plague, and attempted to place a gag order on all media reports related to it.

At the same time, Kinyoun and others were facing additional challenges. Kinyoun was instructed to inoculate "all persons of Asian heritage” using a vaccine that had been developed by Waldemar Haffkine, the first of its kind for bubonic plague. While Haffkine’s work in vaccine development led to him being declared “a savior of humanity,” in 1900 his bubonic plague vaccine was still in human trials, and had not yet been approved for use in the population at large.

bubonic plague san francisco
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  • Scientists perform autopsies on rats. This research ultimately helped curb the spread of the plague.

    Photo Credit: The National Library of Medicine/Centers for Disease Control via Nature science journal

What’s more, the bubonic plague vaccine was only about 50% effective, lasted for only around six months, and was known to cause excruciating side effects. Unwilling to be experimented upon in such a way, the residents of Chinatown resisted the forced inoculation. The Chinese Consolidated Benevolent Association, also known as the Six Companies, helped residents file lawsuits against members of the San Francisco Board of Health.

Related: The Most Bizarre Historical Folk Remedies

As the plague continued to ravage San Francisco, with more than 120 confirmed cases and 119 deaths, President William McKinley himself eventually became involved, working in secret with Gage to oust Kinyoun without ever publicly admitting that the plague was happening at all. It’s a move that has been said to have destroyed the credibility of the American public health system. Taken into account with the racial discrimination and media reports that alleged “the most dangerous plague which threatens San Francisco is not of the bubonic type” but instead “a plague of politics,” and all of this should sound pretty familiar to anyone who has lived through the last few years of COVID-19.

By the time of the general elections in 1902, word of the plague had nonetheless spread across the country, with many other states threatening boycotts of Californian goods due to the state’s denial of the outbreak. Seen as a liability to his party, Gage was not put forth as the Republican candidate for governor in 1902, replaced by George Pardee, a medical doctor whose policies helped to stop the spread of the plague by 1904. Minor outbreaks continued to appear in the region until 1911, when cases dwindled and the plague became exceedingly rare in the US.