I'm curious about how you got that impression. In Canada, smoking is down from 26% in 2001[1] to 15% in 2019[2]. (Cannabis consumption is probably trending upward though). I have no reason to believe that this decline is particular to the US and Canada. Japan has been trending down from 33% in 2000 to 20% in 2020[3]. I expect this will have accelerated since the government made a strong anti-smoking push during the Tokyo Olympics. In fact, this seems to be a trend across the entire developed world, see this chart[4] showing that cigarette sales per adult per day peaked by the 1980s in every developed country surveyed, and all have been trending downward for decades. The US shows up as exceptional mainly in how extremely high its cigarette consumption habits were in the '60s and '70s.
Ah, it was just a much larger shift in the US, especially demographically. It went from 44% of adults (stats not gathered on younger folks, but anecdotally it was ‘cool’ and a lot of highschool age kids smoked) to 13.8% for adults (anecdotally many quite old) and only 8.8% for younger folks.
Traveling outside the US to Europe or Asia (eastern/southern Europe or China in particular) it’s very visible, where in the US outside of a few locations it’s almost invisible now and notably uncommon.
Especially for educated or higher income folks, too.
Canada worked to discourage and regulate smoking more aggressively around 20-30 years ago, and in 20 years we’ve gone from around 1 in 4 people smoking to more like 1 in 10. It steadily trends down.
The US is pretty much the only country to successfully reduce it, near as I can tell (perhaps Canada has had success too?).