How did the American Feminist movement affect the entry of women into the politic sphere?
One of the most distinct ways the Feminist and Suffragette movements impacted the entry of women in to politics is to have moved the discourse of women's rights from private to the public domain. Prior to the Feminist Movement, the roles of women were seen as privatized and ones away from the public discourse of policy and social direction. The idea that women were able to appropriate language that projected themselves and their dreams into the public realm became a major reason why it became feasible to envision women entering public policy and political discourse. The idea of being able to move a group of people who had been socially understood as remaining in the private and being able to move both their presence and roles into the public helped make the transition into politics a plausible and realistic one. Granted, women representation in the political sphere is not as proportionate as the male presence, but there are strides being made with more to be taken.
There have been at least two "feminist movements" in the US. The first happened in the 1800s and was concerned with such things as pushing for the right to vote (which women gained nationwide in 1920).
The second happened in the 1950s to 1970s, more or less. This was the famous "women's lib" movement.
The first of these did not do much to get women into politics per se. There was one woman senator appointed in 1917, and some other high officials, but not many.
It was only after the second feminist movement that women started to be at all common in the political sphere. Follow the link and scroll down to "Women in Politics."