The Introduction to American Government course, and its textbook, is a nearly universal experience for students in American colleges and universities, but what exactly is being taught in this course? Do the textbooks used in this widely taught course accurately reflect the diversity of populations and experiences in the United States? More specifically, how do textbooks for Introduction to American Government cover historically marginalized groups, if at all? This article builds on previous work by analyzing the representation of individual historically marginalized groups to conduct index search and content analyses on traditionally published and openly licensed (i.e., open educational resources [OER]) textbooks. This study finds that American government textbooks include little coverage of any historically marginalized groups, and that OER textbooks are average in this respect, doing neither better nor worse than their traditionally published counterparts.