This marks the day, 90 years ago, when the 19th Amendment became law. Women gained the legal right to vote although many did not, either because of local obstructions; violence in and outside the home; and cultural beliefs about women and politics. Of the women who voted, most voted the same way their husbands or fathers did. A gender gap didn't arise until 1980.
Rep. Bella Abzug got Congress to designate Aug. 26 as “Women’s Equality Day” in 1971. The National Women's History Project has more background, including the original resolution. It leads off:
WHEREAS, the women of the United States have been treated as second-class citizens and have not been entitled the full rights and privileges, public or private, legal or institutional, which are available to male citizens of the United States; and WHEREAS, the women of the United States have united to assure that these rights and privileges are available to all citizens equally regardless of sex ...If only we really were united.