The likelihood of being married is considerably lower for lower levels of educational attainment. Less than half of women with "some college" education were married in 2009. And only one quarter of women with a less-than-high-school education are married. On the other hand, nearly 60 percent of women with a bachelor's degree and nearly 70 percent of women with a graduate degree are married.
So why the big difference?
The staff at the U.S. Census Bureau suggest that marriage is becoming a characteristic of the economically advantaged:
As marriage rates have decreased and cohabitation has become more common, marriage has become more selective of adults who are better off socioeconomically and have more education.However, marriage doesn't "select" people. People select marriage. So I offer a counter-argument that there is larger force at work. Perhaps marriage isn't simply becoming a tradition of the well-to-do. Perhaps as more women choose to go to college, they are delaying marriage, and thus don't enter the "married" category until they achieve at least a bachelor's degree.
Source data: U.S. Census Bureau, American Community Survey, 2005 and 2009