Michigan’s ACT range has definitely gone up over the last decade, including for instate students from what I can tell. Whether that is the same population of students from a generation ago who simply prepped more, or whether UM has become more selective is hard to tell. Maybe the best indicator is fraction of the MI high school graduate population, in which case it is a combination of the two - a little bit more selective for in state students, a little bit higher test scores for the upper tier of the graduating seniors.