Tornado Alley (PROG)

[DragonBear]

I think the CDC has a good idea:

Except to attach the spread from the US to "Asia" is inaccurate.

The first Chinese Labour Corps traveling across Canada occurred 18 January 1917. The first cases in China occurred 1917–1918.

One had the virus spreading in China before 1918. With transit across Canada into Europe, long before the US cases in Kansas showed up.

Also possible is it spread from China Westward through British commerce.

The big question is how did it originate in the US at an isolated army camp in Fort Riley, Kansas? Or did it? Public health reporting in 1918 does not compare to today's standards.