Women are much more eager to vote for socialist/collectivist government programs than men are.
Found this wiki.
http://en.wikipedia.org/wiki/Women%27s_suffrage_in_the_United_States
It has been argued that without women’s suffrage, the Republicans would have swept every election but one between 1968 and 1974. Another result of Women’s suffrage is the steady rise of government spending between the 1920’s and the present, as women are more risk averse than men and support “safety net” type income distribution and social welfare programs such as Medicare, Social Security, and public education.
This came about in direct contradiction to what was expected by some writers prior to the passage of women’s suffrage. In fact, it was stated by one opponent to suffrage that women voters would be “thriftier and less wasteful than men.”