That up to that point, American society considered women as second rate citizens.
The 19th amendment that was passed in 1920 gave American women the right to vote.
Without the right to vote, the women would not have the chance to elect a government representatives that are willing to hear their cause and fight for it during the legislative process. After they obtain the power, women can start to make the progress to pass the law that tip the balance in the society and gave them with opportunities to advance.