(CNN) This week Illinois lawmakers approved the Equal Rights Amendment, a long-proposed addition to the United States Constitution that would ensure equal rights to all Americans regardless of sex.

You would think that 230 years after ratifying its Constitution, the US would have some sort of federal protection like this enshrined in its supreme law.

But the ERA, which states that "Equality of rights under the law shall not be denied or abridged by the United States or by any state on account of sex," has been languishing in Congress since 1923.

After decades of debate, it was passed by both the House and Senate in 1972. But for an amendment to be added to the Constitution, a minimum of 38 states have to sign off. By the time the deadline for ratifications passed in 1982, approvals had slowed to a trickle and stopped short of the magic number.

Recently, with the rise of the #MeToo and #TimesUp movements, there has been renewed interest in passing the Equal Rights Amendment. The vote in Illinois now brings the tally to 37 states -- just one shy of the 38 needed to add the amendment to the Constitution.

Photos: History of the ERA The feminist activists of the 1960s, '70s and early '80s weren't the first to push for an Equal Rights Amendment. Suffragist leader Alice Paul, second from right, fought hard to pass the 19th Amendment -- which earned women the right to vote in 1920. She drafted the first ERA and introduced it to Congress in 1923. Hide Caption 1 of 11 Photos: History of the ERA In 1972, the House and Senate passed the ERA by the required two-thirds votes before sending it to state legislatures for ratification. Three-quarters of the states needed to ratify it, but the ERA fell three states short by its 1982 deadline. Hide Caption 2 of 11 Photos: History of the ERA Gloria Steinem was among the key forces behind the ERA effort in the '70s and '80s. Although it wasn't ratified, most men and women were pro-ERA, Steinem says. Hide Caption 3 of 11 Photos: History of the ERA President Richard Nixon endorsed the ERA after it was adopted with bipartisan support in both houses of Congress in 1972. Hide Caption 4 of 11 Photos: History of the ERA The face of ERA opposition, back in the day, was Phyllis Schlafly, the conservative activist who founded the Eagle Forum. She died in 2016 but said a year earlier that efforts to revive the ERA were "a colossal waste of time." Hide Caption 5 of 11 Photos: History of the ERA Schlafly led protests against the ERA, including this one at the White House in 1977. The group, about 200 strong, was protesting then-first lady Rosalyn Carter's campaign for the ERA. Amendment supporters like Eleanor Smeal, president of the Feminist Majority Foundation, say their real enemy was never Schlafly but big business and insurance companies. Hide Caption 6 of 11 Photos: History of the ERA Democratic Sen. Ted Kennedy speaks at an ERA fundraising dinner in Washington in 1980. Kennedy spent more than three decades as a champion for the amendment in Congress. Hide Caption 7 of 11 Photos: History of the ERA Eleanor Smeal, then-president of the National Organization for Women, left, and first lady Betty Ford attend an ERA rally on the steps of the Lincoln Memorial in 1981. Hide Caption 8 of 11 Photos: History of the ERA From left, Rep. Gwen Moore, Sen. Bob Menendez and Rep. Carolyn Maloney hold a news conference in 2010 outside the U.S. Capitol to call for passage of the ERA. The amendment has been introduced in nearly every session of Congress since 1923. Hide Caption 9 of 11 Photos: History of the ERA ERA supporters like to quote late US Supreme Court Justice Antonin Scalia, who told California Lawyer in a January 2011 issue, "Certainly the Constitution does not require discrimination on the basis of sex. The only issue is whether it prohibits it. It doesn't." Hide Caption 10 of 11 Photos: History of the ERA Supreme Court Justice Ruth Bader Ginsburg, seen here at an annual Women's History Month event at the US Capitol a few years ago, said this when she was asked how she would amend the Constitution: "If I could choose an amendment to add to this Constitution, it would be the Equal Rights Amendment." Hide Caption 11 of 11