Estimate of U.S. prevalence of adults aged 18 and over with any serious medical condition, as of 2018. (CDC map)

A new report from the Centers for Disease Control and Prevention has a map showing which counties have populations with an increased risk of severe outcomes from covid-19. Many are rural, since rural populations tend to be older, more obese, and are more likely to have underlying medical conditions. Read more here: 

https://www.cdc.gov/mmwr/volumes/69/wr/pdfs/mm6929a1-H.pdf