Michaels came up with using in 1969:
Ms. Michaels first encountered the term in the early 1960s. She was living in Manhattan, sharing an apartment with another civil-rights worker, Mari Hamilton. One day, collecting the mail, she happened to glance at the address on Ms. Hamilton’s copy of News & Letters, a Marxist publication.
It read: “Ms. Mari Hamilton.”
Thinking the word was a typographical error, she showed it to Ms. Hamilton. No, Ms. Hamilton told her: It was no typo. The Marxists, at least, appeared to have had a handle on “Ms.” and its historical meaning.
Michaels died June 22 of leukemia.