Schools in general have gotten a lot more competitive, and not necessarily because they themselves have changed much. When I was applying to college, college had not yet achieved the mystical status it does today, where basically the assumption is you had to go to college and get a bachelor’s, at a minimum, to have any hope of a good job, and then in there wasn’t the mania that ‘only the Ivy league will do’, unless you happened to want to go into certain fields. The acceptance rate has also dropped because applying is so easy these days, when I applied to college each college had its own admissions forms, you had to write essays and do things for each school, and not all was that common, and if you add all that up the numbers applying were less…plus keep in mind that you also didn’t have as many kids applying from overseas, especially from China in the last 10-15 years, and India and the like…doing what I did in college, I would not have gotten into the schools I did today, NYU was a big school whose focus was generally centered around commuter students, and because it admitted so many it wasn’t as competitive (and in many ways, I am not happy with what NYU has done, they have gone upscale with their school, it is as expensive as any Ivy, but more importantly they also gave up on their original mission, which often was to allow kids from families that had never gone to college to go and get degrees, they may have sacrificed on their elitism, but take a look at their graduates from back in the day and where they came from and what they did, lot of poor Jewish and Italian kids went there, working class kids, and did well). NYU is very selective, it isn’t quote Ivy league (though it tries to pretend to be), it has a lot of money, but a lot of that is spent IMO in chasing ‘prestige’, so they do things like buy expensive brownstones to lure ‘elite’ professors and so forth. NYU always had top programs within the school, Its math and computer science department was strong when I was there, and only became stronger over the years, the economics department had more than a few notable teachers, and what is now TSOA (Tisch school of the arts) was difficult to get into when I went there, the undergrad business school was not that hard an edmit, but the grad program was, and so forth.
University of Chicago was a very competitive admit even when I applied (and got in), and they had the reputation of being a place where kids serious about learning went, that it wasn’t the “I’ll go there to get into investment banking”, but rather were attracted by many of its well known programs (in Economics, whether I liked their ideas or not, they are an elite institution, in math and comp sci they were up there, in Physics and Chem they were big names).They were in some ways the equivalent of the elite LAC’s in New England with their own particular culture (and yep, the first atomic reaction was done by University of Chicago researchers under the football stadium, I believe U of Chicago also was involved during WWII with the bulk synthesis of Penicillin, or at least I dimly recall that)…
My take on University of Rochester was at one point it was attractive because of Kodak (then) being a major corporation, and they donated a lot of money to its technology departments, and as a result bright kids could get serious scholarships tjhere. I have heard that they have moved even more upscale now, but back in the day that is why ti was like that.
CMU I don’t think has moved that much more upscale, only because when I was applying to school that was considered a major ‘grind’ school, in tech they were up there, in large part because of their endowment, and over the years I have known a lot of people that went there,most of them were serious brainiacs (to use an old term:).
In terms of the ivies, U of P , Cornell, Brown, Columbia and Dartmouth were kind of seen in my day as being ‘lesser ivies’ (and before someone takes my head off, I am not saying I agree with that), that HYP were kind of the ‘senior ivy leagues’, and the rest were merely “great”. There is still some of this attitude, the music program my son did in high school was full of kids in there because they knew Ivies look for serious music students and it helps admissions, and among them there still was the bias towards HYP, some of the kids were really disappointed they got only into “the other ivies”, and Cornell especially for some reason to them was ‘slumming’ (I don’t understand it, given the faculty the place has had, including one of my heroes, Hans Bethe:). Obviously all of the ivies have a cachet, but there is still the ‘old boy’ view of HYP out there, too. (and for the record, I happen to think all of them are great schools, they do attract heavy hitter faculty and students, my only objection is to the idea they are the only great schools or somehow create the only good output in the world, which is silly:).
Northeastern is interesting, back in the early 90’s my sister worked for one of their professional programs (I think it was EMT training). At the time Northeastern was as others said, it was a commuter school, a lot of the kids going there (not unlike NYU) were working classs kids, many of whom were first generation going to college, and so forth, now when I look at Northeastern (the school my S goes to is literally right next to it) and I see the kids going there, it has changed a lot , lot more well off kids judging by clothing and such, and very different vibe, lot more money was put into it.
I would also be careful in defining elite, and admission rates may not be necessarily a great way to tell. To me elite is what a school puts out, its faculty, what their research produces, and more importantly, what their kids go on to do. Schools can game rankings, but more importantly, even if they are now getting kids who are getting X SAT, Y gpa and so forth, what are they doing with them? What are they producing?