The United States Census Bureau says that women bring in 81 cents on the dollar across all industries in the US labor force. So it doesn’t come as a huge surprise that salaries in the supply-chain industries mirror that trend.

Such was the findings of a recent study from the Institute of Supply Chain Management (ISM), which found that the median salary for women in the supply chain sector was $88,000, while men made an average of $108,000. That’s 81.48 cents on the dollar in the case of the progressive supply-chain industries.

The ISN study of 3,000 purchasing and supply chain professionals in the US showed that more women are entering management positions in the supply chain field, but that the salary gap grows with career longevity. Men overall earned an average of 29 percent more than their female counterparts in 2017, but for those with 15 to 19 years experience the field, the gap widened to 48 percent.

On the other hand, pay gaps shrink among more junior positions. Men with less than four years of experience earned two percent more than women last year compared with a 22-percent differential in 2013, according to the study.

According to The Wall Street Journal white-collar jobs “often reward people who work long hours or change positions frequently, steps some women with families may be less likely to take.” But there also has to be a bigger and more basic influence at play: old-fashioned gender discrimination.