I used to think of it as 60 but I know people who are 60 and don’t seem elderly.
I’d say 70 and older.
I’m 53. I’ll be 54 tomorrow.
When I was little, people in their 50’s seemed old. They looked older then than they look now. I just found out recently that Carroll O’Connor was 49 when he started playing Archie Bunker. I didn’t believe it so I googled it and it’s true. When you look at Archie Bunker, he looked old. Edith looked old. Now, in the area I live in, women who are in their 50’s and 60’s look young until they’re old. I specify “in the area I live in” because when I go to other parts of the country, women look more dowdy when they’re older.