A handful of universities seem to control flow of ideas, people in academia, research finds
https://www.sciencedaily.com/releases/2022/09/220921113109.htm
The study, published Sept. 21 in the journal Nature, takes the most exhaustive look yet at the structure of the American professoriate -- capturing data on nearly 300,000 tenure-track faculty (including where they received their own graduate degrees) at more than 10,000 university departments at 368 PhD-granting institutions from 2011 to 2020.
The study reveals that in all fields of academia, most professors come from a small number of institutions.