Salaries for political science faculty decreased in all measured categories between academic year 2014-2015 and 2015-2016, according to the 2015-2016 APSA Departmental Survey.
Both salary amounts and the degree of change varied by the highest degree offered by the department, as well as by the type of institution in which the department is located. Larger departments offering graduate degrees in the field offered higher salaries for all faculty except full-time non-tenure-track faculty, while smaller departments granting only undergraduate degrees tended to offer lower salaries overall.
The 2015-2016 APSA Departmental Survey was administered to 1,243 departments at 4-year colleges and universities offering degrees in courses in Political Science and Government in the United States. 349 departments responded to the survey for an overall response rate of 28.1%.
You can read the full report on faculty salaries here.