How bad was the Spanish Flu pandemic of 1918?
Yes it was a terrible tragedy, but many locales had much worse events fairly recently:
Between 1917 and 1918 New York City’s crude mortality rate increased by 3.173 deaths per 1000 persons. While tragic, the hollow circles in Figure 1 depict 12 other years where the year-over-year increase in mortality exceeded the magnitude of the 1917 to 1918 change. During the cholera epidemics of 1832, 1834, 1849, and 1854 the year-over-year increase in mortality was 3 to 5 times larger in magnitude than what occurred in 1918. As another comparison, the mortality rate in New York City was higher in nearly every year between 1800 and 1905 than the mortality rate in 1918.
The same is true for many other American cities, but here is a picture for NYC:
During the first half of the 20th century, Black Americans in urban areas died from infectious disease at a rate that was greater than what urban whites experienced during the 1918 flu pandemic every single year.
On a different but related topic:
…the evidence suggests that the 1918 pandemic was not a major determinant of U.S. stock market volatility.
That is all from the new and very interesting NBER paper by Brian Beach, Karen Clay, and Martin H. Saavedra, “The 1918 Influenza Pandemic and its Lessons for Covid-19.”