[This paper is part of the Focused Collection in Investigating and Improving Quantum Education through Research.] The modern physics course is a crucial gateway for physics majors as it provides an introduction to concepts beyond the scope of the K-12 education. This study collected 167 modern physics syllabi from 127 U.S. research-intensive institutions using publicly available syllabi (51.5%) and private correspondence (48.5%). Due to the size of the corpus being large enough for natural language processing (NLP) to provide significant insight into the curricular content of a course, but still being small enough for human analysis to remain feasible, both NLP and human-analysis methods were utilized. The use of both methods provided a way to test the newly introduced method of NLP in physics education research and offered a novel tool for cross-validation. Public course catalogs were consulted to identify prerequisites and corequisites with 89.3% of students having completed a course in calculus II or higher. Foundational topics like Newtonian mechanics (94%), electricity and magnetism (84.4%), and waves or optics (77.2%) were frequently required. Most institutions consistently taught quantum physics (94%), atomic physics (83%), and relativity (70%), but there was variability in the inclusion of other topics alongside these three main topics. The study highlights the current modern physics curricula at U.S. research-intensive institutions, emphasizing the importance of a consistent and comprehensive education for physics majors across universities. This insight contributes to the ongoing discourse on optimizing physics education in higher education.