JLang wrote: "There was less population density ,
Post# of 148165
Less travel over smaller distances? Maybe statistically correct, but don't forget what might have been THE crucial factor in spreading the 1918 Flu: World War I. The initial outbreak was probably among the US military in the spring; that fall, the flu hit everywhere. Meanwhile, the US was sending the American Expeditionary Force to Europe.... packed like sardines in troopships for days at a time... in order to then gather in very close conditions in trenches. So the travel was under less sanitary conditions and took much longer, allowing the infection to travel to Europe, where it became (incorrectly but widely) known as the Spanish Flu.
See my film: https://www.pbs.org/wgbh/americanexperience/films/influenza/