Stole this summary from another board regarding AAU membership since the 90's
from the 90s to 2011 the AAU added 5 (UCI, UCD, UCSB, A&M, Stony Brook) and dropped 2 (Catholic, Clark).
They lost 2 in 2011 (UNL, Syracuse), and Iowa State withdrew in 2022
they have added 12 since 2011 (Georgia Tech, Boston U., Utah, Dartmouth, UCSC, Tufts + the 6 announced today).
So there are 5 former members total, Catholic University of America (Washington DC) Clark University (Mass), Nebraska, Syracuse, Iowa St