The Two key dates in U.S. history that really stood out to me as empowering for American women, and in many cases women abroad as a result were...

1776–1807: New Jersey grants women the vote in its state constitution. - A date that really surprised with its early recognition of women's rights. An incredibly outlandish move for that time period, it is way before the date that I personally assumed, baring in mind initial UK impressions of suffrage is very much the late 19th turn of the 20th century. 

A key moment because it paves the way for the women's rights movement galvanising other women around the U.S. and giving them hope.

April 2, 1917: Jeannette Rankin of Montana is formally seated in the U.S. House of Representatives as the first woman elected to Congress. - I picked this as a key date because it is arguably one of, if not the most, senior position ever taken by a woman in the U.S. based on individual achievement. Even though today the pursuit of equal gender rights is by no means a forgotten subject, the 20th. Century was in many respects a century for women in the way that the female image and lifestyle develops so rapidly, and it is all down to showing that if a woman can be in congress how can she not do other things? 

Overall, the significance of these two dates shows the the start of a 150 year journey that caused the rights that women so truly deserve to eventually be delivered, and the date in which a female in congress can start to change institutionalised sexism in the U.S. Political system.