ABT had been a member of AGMA however left AGMA, forming their own union years ago. I am not clear on the history of when it joined and the exact year it left AGMA. My guess is 1980 something when it left AGMA. I can still see the photo of the dancers carrying picket signs in the NYTimes. It is interesting to read that they have voted to return to AGMA under an administration that voted to leave it.
Oh the circle of life!