South Dakota has a higher rate of births to unwed moms than any neighboring state. We have more people, but fewer are getting married: from 2000 to 2011, the marriage rate dropped from 9.1 per thousand residents to 7.5.
And in the middle of that period, in 2006, we narrowly passed a constitutional amendment to protect marriage from those darned homosexuals by banning same-sex marriage.
Let's look at two maps. First, from the Census Bureau report on unwed moms, here's a map showing whether each state's percentage of unwed moms is above, below, or statistically indistinguishable from the national average of 35.7%:
Now here's the latest Wikipedia map of states' policies on same-sex partnerships:
Hmm... that gay-marriage-loving block in the Northeast has about the same or lower rates of unwed moms as God-fearing South Dakota. All those West Coast hippies are having babies within marriage more frequently than South Dakotans, as do those libertines on South Dakota's eastern shores.
So explain to me again how telling a bunch of our friends and neighbors that they can't make a lifelong commitment to each other to raise children helps promote the sanctity of marriage?
Another factor raising the rate, ironically, could be the moral conservatism that intends to keep it down, said Barbara Donaldson, a case worker and former teacher in Sioux Falls. A viewpoint insisting marriage is the one and only path for sexual relations closes off opportunities to discuss responsibilities and consequences, she said.
“When you have a morally conservative base that says you need to be married — end of discussion — most kids these days are going to make their own choices, and that ‘one path’ isn’t the one they’re going to choose,” Donaldson said [Jon Walker, "Births out of Wedlock up in South Dakota," that Sioux Falls paper, 2013.05.06].
Oh, that's right: it doesn't.
I would have guessed young South Dakotans to be good communicators with their children, but if Donaldson is right, maybe people here are still not able to have frank discussions about sex. Repression is rarely a good thing. In Saudi Arabia, even though it's punishable by death, straight men have lots of gay sex (according to this article) because it's too hard for them to have premarital sex with women.
People seem so anxious to define, pigeonhole, classify, judge, but it's not healthy in the gray areas of sexuality in my opinion. Things just don't fit nice.
http://www.defence.pk/forums/middle-east-africa/217211-homosexuals-saudi-arabia.html
I think that there are other factors that you are not considering.
A county by county look at the births out of wedlock would be interesting, especially over the past 60 years.
I think the more education and income you have the less likely you are to have children out of wedlock. That probably wasn't the case 60 years ago but I'll bet it is today. Controversial author Charles Murray wrote a book about the phenomenon recently.