More than 50 years have passed since the Equal Pay Act of 1964, and women are still paid less than men. United States universities claim to be pioneers of social progress and so it is of interest to know whether the gender wage gap exists there. This study sheds light on the academic gender wage gap by comparing the salaries of male and female assistant professors within three years of being hired at selected U.S. public universities. The group of assistant professors are likely to satisfy our exchangeability assumption because early career faculty tend to come with similar experience. Finally, we focus on public university faculty because their salaries are publicly available. The data studied was collected from salary reports from public university systems in 2018 and 2019 under the Freedom of Information Act. Due to the novel way of assigning gender using genderize.io, traditional statistical methods for comparing two populations are not appropriate. For this reason, this study uses permutation-based non parametric tests that are valid for the data. Our study examines the presence of the gender wage gap in U.S. public universities and finds that significantly more women receive lower salaries than men. For example, the proportion of women making less than $10,000 a month is 12% higher than the proportion of men making the same amount. The study concludes that gender disparities within academic disciplines are a considerable factor contributing to the wage gap.