The US has averaged over 30% daily increases in infections for the last 20 days. 1.3 x 1.3 x 1.3 = 2.2x growth every 3 days making that 4 day doubling optimistic. https://en.wikipedia.org/wiki/2020_coronavirus_pandemic_in_t...

New infections are modeled to noticeably slow down once ~1/5 of the total population is infected, but at that point things have already fallen apart.

The US has also been ramping up testing, assuming number of infections is a linear function of known cases is a mistake.

We are not doing 16,000 / 42 = 380x more tests per day on March 20th vs March 1st. It’s not even obvious if we are overlooking a larger fraction of infections today than back then.

Also of note that 30% daily increase I spoke of underestimates the difference between March 1 and March 20th.

It's doubling even faster right now, but that may be more related to increased testing than anything.

Unfortunately, the US is further along the curve than all these sites are showing due to the fact that we didn't have any testing in the beginning (and still don't have enough).

New York City doubled in one day - yesterday simply by having the capacity to do more tests.

Right, which isn't relevant to projecting future new infections.