Given old newspaper reports of "gorillas" and wild men in America's hinterland, and the purported Native American belief in tribes of giants, most skeptical commentators are reluctant to give a defining moment in time to the origin of the sasquatch myth that is comparable to the Kenneth Arnold episode relating to the UFO myth. I see it differently.
I see the sasquatch myth as beginning with Green, Dahinden, Sanderson, Ostman, and Roe. They are the sasquatch founders. Rene was the passionate spark looking for a yeti anywhere he could find it. Green, a convert, was a self-important journalist who was bent on scooping the world. Sanderson, a zoologist, was now making money as a writer of nature and Fortean subjects. Roe dreamed up a story to help celebrate "sasquatch days" and, apparently called on it, sanctified it by swearing to its truth. And tall-tale spinner Ostman joined in with a fairy-tale updated for British Columbians.
Green converted the sasquatch of Indian lore into the British Empire's "Abominable Snowman," the yeti, itself a Darwinian apeman vision of muddled Sherpa lore. He took the Roe and Ostman accounts, along with the Ruby Creek Incident (see posting up thread), and created an enduring legend of the Giant Ape of North America (and contrary to what Roe and Chapman at Ruby Creek said were human). Sanderson, making a living writing up a Fort viewpoint, and the only celebrity of the bunch, entertained his audience dutifully, even if they didn't see the wry and the winking.
It all really started with these guys. The singularities, like the Jacko story and the Ape Canyon story, were dug up and given new contexts. And then came Northern California in the late 1950's, with hoaxer Wallace and company, serious and gullible Jerry Crew, the name "Big Foot," and then John Green to link it all to his yetiized sasquatch.
This origin transpired as cryptozoology was being introduced by maverick zoologists and popularizers of Fortean and occult phenomena. They needed big cryptids to promote to the public. And the rest, as they say, is history.