While women’s suffrage is constitutionally protected, no where does the Constitution prohibit discrimination on the basis of sex. The U.S. is a global outlier when it comes to guaranteeing constitutional equality of the sexes.
Until all women—no matter their gender identity, race, class or any other status—have a constitutional guarantee of equality on the basis of sex, they will have to rely on an incomplete patchwork of state and federal laws to protect their most basic human rights.