Back in April, when New York City was the pandemic’s epicenter, it all made sense. The city has 27,012 people per square mile, the highest density of any major U.S. city. Of course, it would be the nation’s hottest hot spot. But North Dakota and South Dakota have four people per square mile. Montana has seven. As of today, North Dakota’s infection rate is 78 times greater than New York City’s.

It’s immediately obvious that density is not the enemy, as bizarre as that seems. Researchers from the Johns Hopkins Bloomberg School of Public Health and the University of Utah uncovered this surprise in a paper published in June. They found no statistically significant relationship between density and COVID-19 infection rates, adding, “this runs counter to our initial expectations.” But if density isn’t the enemy, then what is?

The researchers suggested several factors that could account for the counterintuitive result, and more recent studies reinforce their hypothesis. The lead author of the paper, the Bloomberg School’s Shima Hamidi, tells Fortune: “Residents of dense places are better equipped to stay at home, reduce their trips, and comply with public health advisories such as stay-at-home orders because of their better access to services such as home delivery.” In addition, those people tend to be more aware of the threat, so they “are more likely to voluntarily adhere to social distancing advisories such as avoiding crowded places (restaurants, bars, beaches, etc.) compared to their counterparts in low density areas.” 

More broadly, says David J. Peters, an associate professor of rural sociology at Iowa State University, “rural America is more vulnerable to COVID-19 than cities are.” That’s because “rural areas tend to have older populations than the national average, with more chronic health conditions that raise the risk of developing more severe cases of COVID-19,” he writes. “They also tend to be home to large group facilities, such as prisons, meatpacking plants, and nursing homes, where the virus can quickly spread to residents, and employees can carry it back into the community.” By contrast, “cities have lower percentages of older residents and people living in institutional settings.”

Attitudes may also play a role, though they weren’t studied in the research. Before South Dakota governor Kristi Noem hosted President Trump at an Independence Day celebration at Mount Rushmore, she told Fox news, “we won’t be social distancing.” Masks were available, but few in the tightly packed crowd of more than 7,000 wore them. The state also declined to cancel the annual August motorcycle rally in Sturgis, against the wishes of some locals. About 250,000 attended. Neither of the Dakotas has a statewide mask mandate.

The notion that density is not the enemy runs counter to the most widely held conventional wisdom on the pandemic. Surging prices of suburban and exurban homes reflect the view that density is bad—that “our closeness makes us vulnerable,” as New York governor Andrew Cuomo said in March. Pre-pandemic, urban planners nationwide focused on increasing density as a way to combat sprawl, but public opinion turned abruptly against that trend. Hamidi and her coauthors believe that’s a mistake. “Our findings suggest that planners should continue to practice and advocate for compact places rather than sprawling ones,” they conclude, “due to several environmental, transportation, health, and economic benefits of compact development.”

It’s still early for all large-scale pandemic-related research; future work will change our understanding further. But those towering infection rates in America’s wide open spaces are telling us loudly that some of our previous thinking was off-base. As apartment prices plunge in Manhattan, just maybe it’s a good time to buy.