Re: private high schools. The number of kids from Illinois’s nationally highest ranked public schools (Like Walter Payton or IMSA) who apply, and then attend, Ivies are a fraction of kids from fancy private HSs in the East Coast which have fewer student achievements, lower student SATs, etc. According to Niche, the top 3 schools in which the kids at Exeter are interested are Harvard, Yale, and Columbia, in that order. For the kids at IMSA, with slightly higher stats, the top three colleges are UIUC, NU, and UChicago, in that order. Among the Exeter kid’s top 10, are all the Ivies but Dartmouth, Stanford, NYU, and Georgetown, with nary a public school. For the IMSA kids, the top 10 did not include a single Ivy, and three were public. The only overlap between the two top 10 lists was Stanford. These are two sets of kids with the same stats and the same achievements.
The differences are that the private school is populated by rich kids, most who are legacies to one Ivy or another, and these fancy private highs schools are a pipeline to Ivies, meaning that more kids will be accepted from them, and at lower stats, than is true for kids from the best public high schools.
It is not by chance that these fancy private schools generally do not rank, which means that they do not mess up the claims of colleges like Harvard, that “of the schools that rank, 68% are in the top 2%”. When you have 25% of your class in the Ivy pipeline, and your best are likely going to places like MIT where legacy doesn’t kick in, you are going to mess up claims about the percentage who come from the top 2% of their class, if your kids are actually reporting their class rank.
It also becomes much more difficult to claim “merit”, when you are only accepting kids from the top 2% of Walter Payton, but are accepting kids ranked as 20th percentile from a fancy private HS which has lower SATs and fewer national awards than Payton does.
Pipeline high schools are, essentially, as much part of the Ivy League admissions system as the college admissions offices themselves.