Lately I've been thinking about marriage and its functional relationship to having children.

Seems that many 21 century marriages are simply tools used by women to leverage control over their men. How feasible is having children without marriage, the world over? In financial terms, legal terms, and, well, female receptiveness terms. Even independent of experience, I expect women will naturally want to keep their legal leverage over a man's property.

I'm curious because I've heard of unmarried couples having children and raising them in America (unusual by the standards where I live, where people are normally expected to get married before having children). How is this possible?