The Equal Rights Amendment was an amendment proposed to be added to the Constitution that would guarantee equal rights for all American citizens regardless of sex.
“Equality of rights under the law shall not be denied or abridged by the United States or by any state on account of sex.” - Section 1, Equal Rights Amendment
The first version of the ERA was introduced by Alice Paul at the Woman's Rights Convention in Senaca Falls in 1923. Then in 1943, it had been rewritten and renamed to the "Alice Paul Amendment". The ERA had later been passed in both the Senate and the House of Representatives, and was sent to states for ratification with a seven-year deadline on March 22, 1972 (https://www.equalrightsamendment.org/the-equal-rights-amendment).
Phyllis Schlafly played a major role on the developnment and ratification process of the Equal Rights Amendment. She completely opposed the passing of the ERA and made many organizations to go against it. https://en.wikipedia.org/wiki/Phyllis_Schlafly
Social activist, writer, editor, and lecturer Gloria Steinem has been an outspoken champion of women's rights since the late 1960s