Vigorously, she mobilized her forces to block what had seemed a sure thing. In short order, state approvals of the E.R.A. slowed, peaking at 35 in January 1977. Several legislatures even rescinded their endorsements. In 1982, despite an extension of the deadline, the clock ran out and the amendment died.

The “anti” arguments ran along various tracks, including a contention by some that the E.R.A. was not needed, given that the 14th Amendment already forbade any state to “deny to any person within its jurisdiction” — including women, presumably — “the equal protection of the laws.”

Mrs. Schlafly preferred frontal assaults. She ominously warned of an America where husbands would no longer be required to support their wives, where anyone could walk into any public bathroom, where women would join men on the front lines of war, where gay men and women would be given “the same dignity as husbands and wives.”

Had she been French, she might well have proclaimed: Vive la différence! “We do expect men to protect us,” she told Retro Report. “You know, it’s kind of like if you’re asleep with your husband and you hear a noise in the middle of the night. I don’t expect my husband to say, ‘Honey, you go on downstairs and find out what that noise is.’ I expect him to go down and protect me. That’s men’s job.”

But even though Mrs. Schlafly prevailed on the E.R.A., she failed in the long run on many levels. Much of what she recoiled from has come to pass: Abortion rights are intact, albeit under siege in some jurisdictions. Same-sex marriage as a right has the Supreme Court’s blessing. Unisex bathrooms are a broadly accepted fact of life, notwithstanding struggles over transgender rights.

And women today not only fill the ranks of the military but are also eligible for combat duty — not that Ms. Schlafly ever approved. “If you know what military combat is, it’s not a job for women,” she said in May.

To Mr. Perlstein, “The anti-E.R.A. side won this particular battle, but I don’t think anyone would doubt who won the war.” He added, “Women take it as a matter of course that there’s more to life than being someone’s wife.”

That point is reinforced in many ways. More than ever, albeit not proportionate to their share of the population, women are chief executives and hold major public offices. Their numbers in Congress are at an all-time high — 20 senators and 84 representatives. A woman, for the first time, stands a good chance of being elected president in November (even if Mrs. Schlafly endorsed her male opponent).

Still, the gender gap is self-evident. Female representation on Capitol Hill, about 20 percent, hardly reflects the overall population. Gender pay equality, while widely recognized as a societal duty, remains elusive. Nationwide, women on average earn 79 cents on the dollar compared with men, and if anything, narrowing the divide has stalled in recent years, according to studies by the American Association of University Women. Reproductive rights are a matter far from settled in some states, like Texas.

As for the E.R.A., ardent supporters never lost faith in the possibility of resurrection. Attempts to revive it over the years, both in Congress and some state legislatures, have plainly not succeeded, but groups like the ERA Coalition keep pushing.

Some strategists propose restarting the process from scratch. Others seek legislation that in effect goes back to the future — to a status quo ante where the 35 state ratifications remain valid, only this time with no imposed deadline for rounding up the required three additional approvals.

Predictably, Mrs. Schlafly viewed all this with a jaundiced eye. As far as she was concerned, female feminists were nothing but sourpusses. More than once in the Retro Report interview, she dismissed them as “disgruntled, unhappy women.”

“I think American women are the most fortunate people on the face of the earth,” she said. “We don’t need any legislation to say any more than that.”

CLYDE HABERMAN, a regular contributor to Retro Report, has been a reporter, columnist and editorial writer for The New York Times, where he spent nearly 13 years based in Tokyo, Rome and Jerusalem. Subscribe to our newsletter here and follow us on Twitter @RetroReport.

This article first appeared in The New York Times.