A county-by-county analysis of the United States by Princeton researchers suggested that rural counties with high populations of people over 60 and limited access to health care facilities could eventually be among the hardest hit by the coronavirus pandemic.

Counties concentrated in the western United States, the northern Midwest, Florida, and northern New England had the highest ratios of hospitalizations to number of people, according to a paper originally published in the journal Nature Medicine. The researchers concluded that allocating emergency resources to hospitals and communities away from major population centers could be crucial to mitigating outbreaks of COVID-19.

The researchers conducted an epidemiological simulation that compared how many hospital and ICU beds each county currently has — according to the American Hospital Association — to the number of coronavirus cases they would experience if the infection rate reaches 20% of the county’s population.

Using 2018 demographic data from the U.S. Census Bureau, the researchers broke down each county’s population by age group, starting at 0-9 and continuing every 10 years through the final designation of 70-plus. Their model then factored in the proportion of each age group likely to become severely ill, with people over 60 being the most vulnerable.