Repeatedly during the White House briefing Tuesday on the coronavirus outbreak, President Trump offered his praise for the state of West Virginia which, as of that moment, had no confirmed infections.

For example, he defended his approach to working with states by noting that some states had more need than others — like West Virginia.

“We have all of this equipment in stock and we’re looking at different sites and a few different locations,” Trump said. “And we’re not going to need them in West Virginia, where so far, I guess they have none.”

“Big Jim, the governor” — referring to Gov. Jim Justice, whose flip to the Republican Party was celebrated by Trump — “he must be doing a good job of that. That’s what’s reported. … West Virginia is the only one that has no cases. So obviously that’s being treated differently than a New York or California.”

Well, that’s not obviously the case, in fact. There are a number of reasons West Virginia may not have any reported cases — and why it may have cases that haven’t been documented.

Update: West Virginia reported its first confirmed case of the virus a few hours after Trump spoke.

Confirmed cases correlate to population density.

Let’s take the examples that Trump cited, New York and California. Both states have seen hundreds of cases and both states, unlike West Virginia, have Democratic governors who have been critical of Trump.

Both are also far more populous states than West Virginia. There are nearly 20 million people in New York and about 40 million in California, compared with under 2 million in West Virginia. In other words, the number of coronavirus cases per 1,000 residents in West Virginia is zero. In New York, it’s 0.05. In California, 0.01.

More importantly, though, there’s been a correlation between the number of cases and population density. The most recent per-county data (from CSBS) shows that link. More density, more cases.

(Data for New York City have combined the city’s five boroughs into one datapoint.)

We’ve added a line showing the county with the most density in West Virginia: Ohio County. There are 31 counties in New York and California with higher population densities than that. All but one have recorded coronavirus cases.

This makes sense, of course. More people packed into a tighter area is the main way in which the virus spreads. Hence the push for social distancing: Getting people away from one another will help stop the spread.

There’s far less international travel to West Virginia

This new strain of coronavirus first appeared in China. Over time, it seeped out into other countries, arriving in the United States by way of people who had visited that country. The first case in the United States was recorded in Washington, from a man who had visited the city in China where the outbreak began.

Transportation Department data show that, in January 2019 alone, there were more than 2 million international passengers traveling through Los Angeles International Airport. There were 1.1 million at San Francisco International. There were 2.5 million at John F. Kennedy Airport in New York.

There were no direct international flights into West Virginia.

West Virginia is also landlocked, so there were no ships docking at its ports, again unlike Los Angeles, the San Francisco Bay area and New York City. Fewer international travelers means a lower likelihood of early infection.

West Virginia hasn’t tested many people.

That doesn’t mean no cases have since emerged in West Virginia. After all, health officials in the neighboring state of Ohio estimate that perhaps up to 1 percent of the state has already been exposed to the virus; it’s hard to believe that no cases have seeped across the river into West Virginia.

But you can’t confirm cases of infection if you don’t test. As of Monday, the state had tested only 84 people, less than one-tenth of the number of people who had both been tested in New York state — and had come back positive. The state’s commissioner for public health further indicated there were only supplies to test about 500 people in total.

The problem here should be obvious. Trump is praising the state and Justice for their handling of the outbreak, but there’s no reason to think that the state’s actions are themselves actually preventing the spread of disease. It may be that the lack of population density in much of the state plays a role, as does the limited number of cases of people seeding the virus. But it’s also almost certainly true that there are cases that haven’t been detected yet, meaning that what the state is doing isn’t preventing cases anyway.

Let’s hope that’s not the case. No state has a higher density of its population that is at higher risk from the virus than Justice’s. Half of the state’s residents are either over 60 years old or have a health condition that means they might face complications should they contract covid-19, the disease caused by the virus.

The governors of New York and California, however much they disagree with Trump politically, are at least complying with the federal government’s advice about containing the virus. Yet Trump, who’s spent more than a month downplaying the spread of the virus and insisting that all is well, seizes upon West Virginia (and its Republican governor) as an example of doing it right.

Justice, meanwhile, is making his own assertions about the virus: State residents should go grab a bite at a local restaurant.

If Justice is looking to see cases quickly begin to appear in his state, that’s a good way to do it.