Millions of Americans on Aug. 21 are expected to travel to prime locations across the country to view a rare total solar eclipse as it passes from Oregon to South Carolina. The last time a total solar eclipse was visible across the nation — from the Pacific to the Atlantic — was in June 1918.

But many of the locations offering the best view of the eclipse are in rural areas with limited health care infrastructure.

The Department of Health and Human Services (HHS) has released a planning guide to help local emergency health care planners and providers prepare for the event.

The resource, released by HHS’ Office of the Assistant Secretary for Preparedness and Response, includes fact sheets, checklists, locally developed guidance documents, and news articles on eye safety, injury treatment, and planned mass gatherings in rural and urban areas. Parts of the guide are specific to the eclipse event, but some portions can apply to any mass gathering.

The path of the total solar eclipse on Aug. 21.