Post #902: The US third wave. Oddly orderly.

Posted on November 30, 2020

Source, here and below:  NY Times Github data repository.

The graph above is the US pandemic since April 1, by state.  As you can see from the height of the peak, the rapid growth in the upper Midwest and Mountain states was unprecedented.  But at this point, it looks like almost all of those high-growth-rate states have peaked.  And, weirdly enough, almost all of them at the same time.

Maybe that’s some artifact of Thanksgiving, but offhand, I don’t quite see how.  The states at the very top of the graph began to peak (in hindsight) one to two weeks before Thanksgiving.

For sure, this isn’t a consequence of recent actions by some of those state governments.  As discussed in my just-prior post, any consequences of (e.g.) mask mandates in IA or ND will begin to show up only toward the end of November.

Below is the tail-end of the same graph, starting 10/1/2020.

By eye, the lines for the various states sort themselves into three orderly groups.

  • Everything above the 100 new cases/100,000/day line shows a sharply-defined peak.
  • Everything from 60 to 100 new cases/100,000/day appears to show a broad, shallow peak, roughly coincident with the sharp peaks in the high-growth states.
  • Almost everything below 60 new cases/100,000/day does not year appear to have peaked.

Most of the lines 100 and above are for upper Midwest and Mountain states.  Most of the lines 60 and below are for East Coast and Southern states.  And the lines in the middle are a bit of a mixed bag.

I have no real idea what might be causing this.  Or whether I’m just reading too much into the graph.  I’m just noting how orderly and geographically clustered the third wave appears to be.  And that, for now at least, in the areas with the highest recent growth rates, the third wave appears to be peaking.

Here are the numbers, sorted in descending order of new cases/100,000/day, showing how far past peak each state is, and by how much.  E.g., South Dakota still has the highest rate of new cases/100,000/day, but the peak rate occurred 15 days earlier, and right now they are one-third (33%) below that peak rate.

States where the peak occurred recently, and where the difference from the peak is small, are states there the rates are probably still climbing.