Influenza Epidemic of 1918 in Butler County, Pa.-- Part 1: In U.S. Started at Fort Riley in Kansas and Spread

From the Butler County Historical Society  "Influenza epidemic of 1918' by P. Schultz.

While thousands of men were being maimed and killed in Europe during WW I, even more so  were being killed world wide by an unseen foe.  The influenza epidemic of 1918.  It did not confine to Europe, but spread all over the world, infecting 20 to 40% of the earth's population and killing over 20 million.  Some 500,000 of those deaths took place in the United States.

The exact origin of it is not known, though first cases of it in the United States were reported from Fort Riley in Kansas in arch 1918.  It took six months to spread to Pennsylvania where it started in Philadelphia and spread from there to the rest of the state, reaching the western part of the state by September.

--Cooter