I suspect that is the order of units produced.
The ones in South America make a “F-200” or somesuch that is actually the F-150 of 10 years ago.
(I was a semi-major stockholder of Ford some years ago, and still get all their prospectus (prospecti?)).
I suspect it is alphabetical...
My initial research shows that the new F-150 is made in Dearborn and Kansas City, NOT Mexico.