I did not look into rankings when I applied and I ultimately think that "rankings" vary based on what you want out of your PhD and your particular needs as an individual.
My own ranking system considered compatibility with the department, stipend amount, healthcare (What is the deductible? Is dental and vision included? Are dependents covered ?), the mean and median rent in the city (Will I need a guarantor to have my own apartment because the stipend is so low?) , teaching responsibilities (Is there a union?), alumni job placement, and summer funding.
My focus overlaps with the museum/visual studies so I also narrowed down by applying to programs with a strong Museum Studies/ Public History department and applied to work with faculty who had some form of affiliation with Art History or Museum Studies in addition to their American studies appointments. Additionally, I looked up fellowships POI's and students had, their existing relationships with various cultural institutions, and any ongoing consulting/advisory roles.
For this reason, some of the "top" schools did not interest me but that simply means that it was not a good fit for my researc and standard of living.