The gap between median annual salaries for men and women with professional degrees (all degrees: bachelors, masters, and PhD) in the U.S. was $24,000 in 2008 (latest available data from the National Science Foundation). The gap for Science and Engineering professions by comparison was $15,000, and for physical sciences $16,000.
The ACS Salary Comparator is a powerful tool showing comparative salary information for men, and women in specific occupations and geographical areas. The Comparator is an ACS member-only benefit, and cannot be accessed by people outside of the organization.
Information gained about the average salary for a job in a specific area of the country can be a powerful tool in the negotiation of a starting salary or for discussions about a raise, but you should be careful to choose the average salary for a male. Don’t quote the salary for a woman in that position. That number is for your information only.
http://www.nsf.gov/statistics/wmpd/pdf/tab9-16.pdf
National Science Foundation, National Center for Science and Engineering Statistics, Scientists and Engineers Statistical Data System (SESTAT), 2008.