Courtesy of @Healthline, here is an informative review of the worst epidemics in the US, from smallpox to typhoid Mary, polio and beyond. You might want to add something stiff to your drink before reading further...
https://www.healthline.com/health/worst-disease-outbreaks-history#7

Caveat: this thread should *not* be construed as any sort of argument about the seriousness or severity of the current #coronavirus pandemic, which will certainly pass polio '52 in terms of overall impact.

#Covid19 #COVID19Pandemic

If your takeaway is that coronavirus is less dangerous than any of these, you're missing a whole lot of points about how people lived, what medical treatments were available, and who was even counted...

I daresay if SARS-CoV2 had been loosed in the US in the early 1800s, it probably would've killed almost everybody, because most of the biomedical innovations pertinent to fighting lung disease didn't arrive until much later:

1896 - Francis Williams - first US chest X-ray
1928 - Alexander Fleming - penicillin
1928 - Philip Drinker - mechanical ventilators / "iron lung"
1934 - Hans Andersag - chloroquine

... and we didn't even have isoniazid 'til the 1950s, azithromycin 'til the 1980s, etc. These are well known to some of us for staving off tuberculosis, pneumonia and similar. Yep I've been on all of 'em, courtesy of growing up in Zimbabwe.

Caveat 2: to get a sense of the impact, you need to do a sort of "inflation adjustment" wrt/ population. For example:

Smallpox took 844/5889 in Boston, ~14%. A staggering number, but the effect on native people was *far* worse... almost 3/4 of our native population perished.

The ~5000 lives lost to yellow fever in Philadelphia represent ~10% of the city's [counted] population.

The ~1849 cholera wave took 4500 lives in St. Louis, which was ~7% of the [counted] population of ~63,000. It probably took a similar percentage of lives in New Orleans...

but the large number of enslaved people there makes me wonder who was even counted.

The so-called "Spanish Flu" of 1918, which did ~not~ come from Spain, claimed ~250-700 thousand lives in the US. With a population ~100 million... ~4% of the [counted] US population perished.

I provide this with some sad apology to those in countries where pandemic outcomes were far worse than those enumerated above. The US has actually done pretty well against pandemics. There are plenty of examples of mass-fatality pandemics in (pre)-developing countries...

...and you certainly don't have to go all the way back to bubonic plague to find them. Ebola sometimes takes ~100% of the population in some affected areas, which is why it doesn't spread, globally.