As a general rule, American men earn more than American women. This holds true across industries, across education levels, and across states. But, there's at least one big exception: part-time employees.
In 2012, women who worked less than 40 hours a week generally out-earned men who spent the same amount at their jobs. If they worked 35 hours a week, they earned about 11 percent more. If they worked 25 hours a week, they earned about 4 percent more.