I think it has a lot to do with current students and resources. Each school devotes different resources to different areas. A lot of it can be quickly gleamed from its information page.
On their graduate studies page, Notre Dame mentions their leading scholarly journals are Religion and Literature, Early American Literature, Shakespeare Survey and Nineteenth-Century Contexts. They also mention that they're a member of the Folger Institute & the Folger Shakespeare Library. The Folger Institute describes itself as the following " The Folger Institute is a center for research in early modern humanities at the Folger Shakespeare Library." There are other things that ND could have mentioned earlier but it chose to empathize that instead and made it so people would stumble upon their page if either of the two terms were searched.
On the Graduate Programs page: Notre Dame states the following:
Ph.D. students are trained to combine scholarly expertise in a research area with the literary range necessary to be effective professionals, teachers, and colleagues. The English Department has close ties with Notre Dame’s other leading humanities departments such as Theology, History, and Philosophy as well as deep bonds with strong record of collaboration with world-class programs such as the Keough-Naughton Institute for Irish Studies and the renowned ND Medieval Institute. Key alliances and opportunities include the following:
On the about page, Notre Dame also lists Related Programs and Institutes. Gender Studies gets a mention early on, but doesn't do anything to grab attention elsewise. Second on the list is the Keough-Naughton Institute for Irish Studies; interesting because it's name which usually means the school is heavily invested in it. They also have a Medieval Institute (this is also the second mention for both the Medieval Institute and the Keough-Naughton Institute; they want you to pay attention to these) and have a John J. Reilly Center for Science, Technology and Values page. They also make mention of a Screen Cultures Graduate Minor and make mention that it is research in the study of film, television and other screen-based media. ND could have highlighted anything they wanted to, but this is what they chose. On the English landing page, ND also highlights some new faculty being hired. These faculty have expertise in global and multicultural literature and also mentions that they have close ties to Notre Dame's Latino Institute. To me, this showcases that this is an area that Notre Dame might be looking to expand in the future. Recent hirings are useful because it helps showcase where a program is considering going. It might also showcase where the university might believe that there are more job openings to be had in the future.
Looking at another school ranked nearby, Washington University in St. Louis paints a different picture.
WashU's second paragraph states the following:
" While our program is rooted in the materials of literary history, medieval to post-postmodern, interdisciplinarity is more than an aspirational slogan here. It is no accident that English faculty members founded both the university’s American Culture Studies major and its Interdisciplinary Project in the Humanities, or that our professors have headed the campus-wide Center for the Humanities and the Modeling Interdisciplinary Inquiry postdoctoral program endowed by the Mellon Foundation. Many of our classes are designed to promote movement across humanities units and disciplines, from History to Comparative Literature, African American Studies to the recently established Center on Religion and Politics. As a complement to their grounding in Anglophone literature, our PhD students may earn certificates in American Culture Studies, Film and Media Studies, Translation Studies, Women, Gender, and Sexuality Studies, Early Modern Studies, and Data Science in the Humanities. The Humanities Digital Workshop, co-directed by an English professor, offers summer fellowships during which graduate students design and build digital humanities projects alongside Washington University faculty."
From the way they stress things, Interdisciplinary seems to be a big thing there. I'm led to believe that they encourage their students to pursue a graduate certificate in any of the fields they've listed. Looking through the Faculty Listing by Field, I see a description of what each subfield is focused on. I also see that the faculty list is smaller because the department is smaller. I see lots of names for the following fields though: Modernism (8), Theory and Criticism (8), Poetry and Poetics (6), Literature and Religion (9), Literature and Politics (7) Gender and Sexuality (7), Drama (4), Book History (6), African-American Literature (4) 20th/21st Century/20th Century and Later American Literature (9), 19th Century American Literature (6), Early Modern Literature (5). There are other things listed but with the exception of Book History and Early Modern Literature, the focus here seems to focus on the 19th, 20th, and 21st Century. This is the second time they've made mention of Gender and Sexuality so they might want people to take notice of that. It's also their second mention of African-American Literature. They also seem to have more people employed within American Literature (at least during the later half) and they have a considerable amount of people mentioned in Modernisms. Theory and Criticism could expand to just about anything. Drama usually is a blanketed term for Shakespeare but they've expanded it to include contemporary drama, which a lot of programs won't go as far. The biggest takeaways here are interdisciplinary, modernisms, gender and sexuality and American Literature post 18th Century. African-American Literature and Women, Gender, and Sexuality Studies also seem to be encouraged as do other interdisciplinary fields. This sounds like a place where dual appointments might be possible.