Earlier this week, President Trump praised the state of West Virginia for its efforts in fighting the coronavirus outbreak that has spread across the country. West Virginia, Trump said, was “doing a good job,” an effort he contrasted with states like California and New York.

After Trump’s comments, we looked at one possible reason for West Virginia’s exceptional position as the only state without any confirmed cases. What were the factors at play? Did the state benefit, for example, from being less densely populated than parts of California and New York? There was a correlation between the two, after all; the more populated counties in those states also had the most confirmed cases.

New York Gov. Andrew M. Cuomo (D) on March 19 announced a series of financial measures for New Yorkers facing financial hardship during the coronavirus crisis. (Reuters)

That tends to hold as we expand outward from just those two states. New York City has more cases than any county in the country, according to data compiled by the Conference of State Bank Supervisors. (The city’s five boroughs are tallied together in that data set.) In counties with reported cases, there are generally more confirmed cases as population density increases.

If we look at every county, grouping together case totals and population densities in roughly equivalent buckets, we see most of the counties without reported cases are relatively lightly populated. Of course, most counties in the country have about 10 people per square mile.

What’s important here is the link between density and confirmed cases. None of the most lightly populated counties have confirmed cases; most of the counties with the highest population densities have confirmed cases.

It’s impossible to consider this question, though, without considering the slow rollout of testing for the virus. There have been numerous examples of people seeking a test for the novel coronavirus but who have been unable to obtain one. Trump himself has in recent days suggested people don’t necessarily need to be tested. (Reporting suggests Trump has been eager to keep the number of reported cases low.)

Data compiled by a crowdsourced effort called the COVID Tracking Project shows there’s not a strong correlation between the density of a state’s population and the number of tests that have been conducted.

You’ll notice that the states with the most cases — New York, Washington, California — have also conducted the most tests. This is somewhat self-fulfilling.

“Over 50 percent of the cases come from three states,” coronavirus task force member Deborah Birx said on Thursday. “This is why we continue to prioritize testing in those states.”

Limited testing was probably a factor in West Virginia’s not having recorded any cases as of earlier this week. The state had confirmed fewer than 100 tests at the time Trump spoke.

It’s probable, then, that the reason New York City has the most reported cases is a function of both its density and its testing. Without having broader testing, though, it’s impossible to know how much of a role that density plays.

Interestingly, while there’s a wide gap in concern about the virus by party, there isn’t a big gap by the type of community in which people live. Those in rural areas — who tend to be more Republican — express little more indifference than those who live in more populous places.

A few hours after Trump praised West Virginia’s handling of the coronavirus, the state announced that it had its first positive test. It was in Jefferson County — one of the state’s most densely populated.