"I wouldn't pin it on one thing," Landivar says. "You can look at education. You can look at work hours. You can look at industry. Women are more likely to be in elementary and secondary schools and less likely to be in hospitals," which tend to pay more.
Landivar says men are more likely to acquire professional or doctorate degrees and to gravitate towards higher-paying specialties. For example, only 1% of employed nurses in the United States are nurse anesthetists, yet 41% of them are men. The specialty pays, on average, $162,900.
While the census study does not look specifically at family demands as a factor in the pay disparities, Landivar says there are numerous studies that suggest that women with children are more likely to work fewer hours and don't have the schedule flexibility of their male colleagues.
The study also found that: