Well at UChicago, for example, I know for certain the lowest was a 22 ACT because they list the range of scores.
Duke does a kind of super score, but they explicitly state they won’t recalculate a new composite score so I don’t quite know how that works. UPenn is the only Ivy that I know super scores the ACT. Stanford also super scores the ACT I believe. I would also be dubious of a 29 being “just fine” for Harvard unless you are Malia Obama. I’d guess that 30 is around how low ad coms are willing to go for non super hooked i.e… huge legacy, donation or highly recruited athlete, but who knows. I heard of students who were homeless or lived in extreme poverty that got accepted with only 28/29.
Any other schools you can think of that you wouldn’t think super score ACT?