The voting women

On this day, August 19, 1920, Tennessee became the 36th state in America to ratify, 50 to 46, the amendment extending equal suffrage to women in America. 

While there is no cut off date for historical events like these, it could be said that the first agitation for women's suffrage was launched in 1839, when Lucretia Mott, a Pennsylvania Quakeress, was upset because she was denied a seat along with her husband to a world slavery congress held in London.

In 1920, there were around 26,000,000 women eligible to vote in the United States.

The historical trajectory of the women's suffrage movement can be found here.