Not only do women enter college at higher rates than men, but they're less likely to drop out once they get there. Female grads now account for about 60% of U.S. bachelor's degree holders. It turns out that persistent wage gaps in the labor market play a big part in motivating women to finish school. In the short term, men who drop out face no financial penalty in their entry-level salaries. Women, on the other hand, pay a steep price right away for dropping out, since female dropouts earn entry-level pay that averages $6,500 a year lower than what their male counterparts earn.

"Female dropouts simply face worse job prospects," the authors observe. "They are more likely to be employed in lower-paying service work, while men who drop out have more opportunities in higher-paying jobs in manufacturing, construction, and transportation."