More people have been confirmed infected with the coronavirus in New York state than anywhere else in the country. There’s some uncertainty to that figure, just in the sense that the slow ramping-up of testing for the virus means that many cases there and elsewhere went undetected. But New York was clearly the hardest-hit based on death toll alone; nearly 30,000 residents of the Empire State have died of covid-19, the disease caused by the virus.

These days, though, New York is a success story. So, too, are New Jersey and Connecticut. While in early April, those three states were seeing about 16,000 new cases each day, they added only 1,000 on Tuesday. Now, most of the new cases are coming from Texas, Florida, California and Arizona. Arizona has been particularly worrisome, adding dozens of new cases per 100,000 residents each day, easily the highest per capita rate in the country.

So on Wednesday, the governors of New York, New Jersey and Connecticut announced a new policy in which visitors from nine states would be encouraged to self-quarantine for two weeks upon arrival in their states. Those nine states — Alabama, Arkansas, Arizona, Florida, North Carolina, South Carolina, Texas, Utah and Washington — are largely red states and, between them, added more than 16,000 new cases on Tuesday. Those states added only slightly fewer new cases than the rest of the country, minus the three blue states imposing the new quarantine recommendation.

Six of those states are among the 10 that saw the largest per capita increases in new cases on Tuesday. The exceptions are North Carolina, Utah and the only blue state on the list, Washington.

While the pandemic was once largely the domain of blue states, thanks to the spread of the virus in the New York City region earlier this year, that flipped earlier this month. Throughout June, it has been red states — again led by Texas, Florida and Arizona — that have added the most new cases. While President Trump and his allies argue that increases are largely a function of additional testing, that’s not the case.

One implication from that shift is that it potentially reflects differences in how red and blue states have responded to the pandemic, with Democrats more broadly embracing containment and prevention measures than Republicans.

But the state-level data also gives a somewhat skewed picture of how the pandemic has changed. In reality, the spread of the virus has shifted in complicated ways.

For example, as we reported last week, it’s still the case that counties that voted for Hillary Clinton in 2016 have seen more new daily cases than counties that supported Trump, if more narrowly.

There are two ways to look at this. The first is the overlap between how states voted and how counties voted, allowing us to break counties down into four groups, from Clinton counties in Clinton states to Trump counties in Clinton states and so on. Then we can look at margins. How do dark-blue counties compare to lighter-red ones, for example?

The answer is interesting. It continues to be the case that counties where Clinton won by the widest margins are adding the most new cases, as seen in the dark-blue line on the graph at right below. But it’s also the case that Trump counties in Trump states have added the most new cases.

How is that the case? Because counties that heavily voted for Clinton are often cities, including many cities in Trump states. (Austin, for example, or Miami.) You can see on the graph at left above that Clinton counties in Trump states are adding cases at the second-fastest rate. Trump counties in Clinton states are adding cases the most slowly.

Why? In part because not many people live there. These are often rural counties, like ones in California or New York, for example. Those counties make up the second-largest number of counties but the smallest total population.

If we control by population, the difference between red and blue states widens, with red states now adding new cases at nearly twice the per capita rate as in blue states. Blue counties continue to add more cases per day as a function of population than do red counties.

Again, though, that varies depending on the type of county. On a per capita basis, Clinton counties in Trump states are adding cases faster than any other group — although counties that Trump won by 10 points or less are adding more cases per capita still.

The graph at right above reveals an interesting phenomenon: Overall, counties are adding cases per capita, regardless of the 2016 vote. In recent weeks, only Trump counties in Clinton states are not seeing an increase in per capita cases. Clinton counties in Clinton states are adding cases, per capita, thanks in part to big increases in Los Angeles County.

It’s not exactly clear how New York, New Jersey and Connecticut established the metrics used for recommending quarantine or why it ignores states like California. It is clear, though, that the locus of the pandemic has shifted to states that were more likely to support Trump four years ago. However, the fact that only Trump counties in Clinton states have seen both static per capita and overall rates of increase in recent weeks complicates attempts to overlay this shift onto politics itself.