As for Chicago's supposed success story in terms of reduced smoking rates in the first year after hiking their age limit to 21 in 2016, note that Chicago also recently hiked their cigarette tax as well, to make their cigarettes some of the most expensive in the nation. Pennsylvania also hiked their own cigarette tax while leaving their age limit at 18, and if anything Philadelphia has seen more progress in reducing teen smoking than Chicago from 2013-2017 according to the YRBSS. Thus, no causal link has been proven.
And while the Tobacco 21 movement luurrrves to gloat about their very first victory in the Boston suburb of Needham, MA, they conveniently ignore another Boston suburb, Cohasset, where teen tobacco use actually increased in the year following enactment of their own local Tobacco 21 law.
Some may dismiss the relevance of tobacco age limits to alcohol (or cannabis), of course, but keep in mind that just a few years ago, Tobacco 21 advocates actually predicted that raising the age limit for tobacco to 21 would be more effective that raising the drinking age to 21 was in the 1980s. Tobacco is far more addictive, which in economic terms means that while the short-run elasticity is lower than for alcohol (or cannabis), the long-run elasticity is higher than for these other substances. And easy access to a daily or almost daily source is thought to be far more important for tobacco as well. Thus, the failure of Tobacco 21 laws to have any meaningful impact on teen and young adult smoking rates would also apply a fortiori to alcohol and cannabis as well.
And the fact that Big Tobacco has now recently jumped on the Tobacco 21 bandwagon (yes, really), after at least feigning opposition at first, shows that the movement has jumped the proverbial shark, and is now tainted as well. Strike three, yer out!