The term "Sasquatch" was coined in the 1920s by J.W. Burns, a school teacher at a British Columbian Chehalis reservation. Burns collected Native American accounts regarding large, hairy creatures said to live in the wild. Loren Coleman and Jerome Clark wrote that Burns's "Native American informants called these beasts by various names, including 'sokqueatl' and 'soss-q'tal'" (Coleman and Clark, p. 215). Burns noted the phonetically similar names for the creatures and decided to invent one term for them all. That name, Sasquatch, happens to be similar to the word for the beast in the Chehalis dialect of Halkemeylem, sesqac (c=ts). Interestingly, proponents note, Chehalis is in the area where historic Bigfoot sightings are densest, and is generally considered to be, if anywhere is, "Sasquatch territory." The Sasquatch is, in fact, a local clan totem and the band is nonchalant about the creature's existence, except to say that the creature is camera-shy and would rather be left alone.
Over time, Burns's neologism came to be used by others, primarily in the Pacific Northwest. In 1929, Maclean's published one of Burns's articles, "Introducing British Columbia's Hairy Giants," which included the word "Sasquatch" in describing the enormous creatures.
After widespread publicity surrounding the 1958's Bigfoot reports from Humbolt County, California, researchers began searching old newspapers and documents for similar accounts, thus rediscovering and popularizing Burns's term.
To some ears, "Sasquatch" has a less sensationalistic association than does "Bigfoot," and is consequently more popular among researchers who strive for legitimacy.