Labor economist Francine Blau discusses the causes of the pay gap:
I've seen some studies where, even when controlling for measured factors, women will get less training than men. Mentorship has been a long-term issue, especially in male-dominated areas, or areas where the senior people are men. People still tend to identify of younger colleagues of the same sex. So they may be more supportive, encouraging and helpful to young men than they are to young women.
Map by Chris Kirk, who comments:
In every state, women make a fraction of what men make. In some counties, they make half as much—or less. Women in Utah have it the worst. There, the average working woman makes 55 cents for every dollar the average working man makes. The state is followed closely by Wyoming, at 56 cents; Louisiana, at 59 cents; North Dakota, at 62 cents; and Michigan, at 62 cents. The best states for income equality are Hawaii, Florida, Nevada, Maryland, and North Carolina. In each, women make about three-fourths of what men make.
The Dish 