My question is about the reading "negative five" sometimes used for $-5$, instead of "minus five."
It's a follow-up to this question: "Negative" versus "Minus"
Putting together all the answers given there, it seems that the original reading of $-5$ was "minus five," but sometime in the 1960s there was a trend in math education to start saying "negative five" instead, supposedly in the belief that it better distinguished the unary operation from the binary one in "$8-5$." Based on the answers, it seems this trend never caught on in the U.K. and Ireland, but it did in the United States, to such an extent that "negative five" now strongly predominates among the younger generations in the U.S. Nothing is said in the answers about other English-speaking countries, such as Canada or Australia.
My question is: How did this trend originate? Was there a specific, identifiable proposal made at some point that was particularly influential, or did the change spread "organically," so to speak? Which textbooks were most responsible for popularizing this phraseology in U.S. schools?
If there are any well-researched articles that discuss this issue from a historical perspective, I'd appreciate a reference.
Incidentally, I am Canadian and was born in the 1970s, and I had never encountered anything like "negative five" until I started teaching people born in the 1990s.