The pandemic began in the US in March 1918, at a crowded army camp in Fort Riley, Kansas. Then, the transport of hundreds of thousands of infected troops in close physical contact between camps caused influenza to spread quickly even before troops gathered in East Coast ports on a route to France. The troops brought the influenza to the ditches of the conflicting armies. And to other parts of Europe and elsewhere.
More than 25% of the U.S. population became sick, and 675,000 Americans died