In the 80s, people could get free cig packs on plane flights, and at auto/horse races.
People could buy cigs at any age in the early 80s. Til places started enforcing the old under 18 law for buying tobacco in the US. I heard once.86 was the year. But I'm sure lots of stores/gas stations still sold cigs to kids and teens for the rest of the 80s.
The modern Min age for buying tobacco/e-cigs in my home state is 21.
In a span of 35-40 years, we went from an era where anyone could buy cigs to a modern era where Even 18-20 year olds can't legally buy cigs. Never mind the fact smoking was socially acceptable before the 2000s.
I bet in the 60s, the actual US smoking rate was more like 80-85% when I count all of those under 18 kids/teens who bought cigs and smoked themselves.