The title is incorrect. This is a ranking of the US news top-25 universities, with an additional tag noting the number of congressmembers associated with the school. If actually ordered by congressional representation the top-3 would be: 1) Harvard 2) Yale 3) Georgetown
That's true, the priority of U.S. News and World Report reflects not just the popularity of that particular list, but that most of those schools have fairly canonical names that are easy to text-mine against ("text-mine" in the most crudest form, string matching and some regexing)...this project started out as an attempt to find out how many Congressmembers had reached various levels of higher education (e.g. B.A.,B.…
So mine the membership list for the members' names and the URLs of their personal Wikipedia pages, then mine the info box on each personal page for university affiliations. The links will allow you to disambiguate universities with similar names.
Pages also exist listing the membership of almost all former U.S. Congresses, so you could repeat the process going back in time; it would be interesting to see how affiliations have changed and diversified (or not) over the years. A similar process would work for finding the academic affiliations of members of the U.S. Supreme Court and the president's cabinet, as well as of state governors; it might even work to find comparable information for some sets of foreign poliicians (e.g., British MPs or members of European Parliament).
(And I agree with arcanus; you should change your page to sort by the count of affiliated members of Congress, not U.S. News rank, as it's the former that is the information being presented, not the latter.)
0. https://en.m.wikipedia.org/wiki/114th_United_States_Congress