More important, Cahn and Carbone also acknowledge one of the more polarizing aspects of the “blue family” model. Conservative states may have more teen births and more divorces, but liberal states have many more abortions.

Liberals sometimes argue that their preferred approach to family life reduces the need for abortion. In reality, it may depend on abortion to succeed. The teen pregnancy rate in blue Connecticut, for instance, is roughly identical to the teen pregnancy rate in red Montana. But in Connecticut, those pregnancies are half as likely to be carried to term. Over all, the abortion rate is twice as high in New York as in Texas and three times as high in Massachusetts as in Utah.

So it isn’t just contraception that delays childbearing in liberal states, and it isn’t just a foolish devotion to abstinence education that leads to teen births and hasty marriages in conservative America. It’s also a matter of how plausible an option abortion seems, both morally and practically, depending on who and where you are.

Whether it’s attainable for most Americans or not, the “blue family” model clearly works: it leads to marital success and material prosperity, and it’s well suited to our mobile, globalized society.