The Spanish flu pandemic of 1918, which struck 20 million people, killing 200,000 Americans, directly followed the massive movements of people during World War I. Mixing Americans from diverse regions during the mobilization for World War II created a big viral mixing bowl that blended the poliomyelitis virus into people from every corner of America. The widespread outbreak of polio in the late 1940s and early 1950s was the direct result. The popularity of air travel had eliminated the need for such dramatic world events to cast the seeds of apocalypse.
