Edward Michaels says there was a flip in the 70s/80s when black Americans began saying "ont". This certainly didn't happen in the Detroit area. I'm 70 years old and my family including aunts, uncles, cousins and grandparents, and every child I grew up with and their parents all said "ont". If there was a flip here, it must have happened before I was born.

I live in lower Michigan (grew up in Detroit). I've noticed that most of the white people here say "ant". I and most black people say "ont" or "ontee". I've also noticed that a few of the people from the deep south (or whose families are from the deep south), both black and white, say "aint".