I'm also not sure on your argument for how "young men" cause crime. Where are you wanting to start, exactly? Do we have numbers that show a higher population of males in the US than in Canada over that time period?
Criminals skew young and overwhelmingly male.[1]
>Do we have numbers that show a higher population of males in the US than in Canada over that time period?
It appears the baby boom was about the same size or slightly larger in Canada than the US.[2] As you can see from my first post, there also was an increase in crime in Canada during the same time period as in the US, but not as pronounced.
Unlike Corn, who is claiming that leaded gasoline is the primary cause of crime, such that it explains the entire or nearly the entire late 20th-century rise and fall in the US crime rate, I am making the much more conservative claim that the ratio of young men in a population is a cause of crime.
Indeed, as I said, the Baby Boom was not large enough for it to have been the primary cause of the US crime wave. (Although it might be sufficient to explain the relatively-smaller Canadian crime wave over the same period).
[1] https://i.imgur.com/2WscI1P.jpg — The chart understates the correlation between youth and crime, because prisoners might be serving multi-year sentences, they may have got away with other crimes prior to those they're serving time for, and first-time offenders are more likely to receive a shorter or no prison sentence than recidivists are.
I'm still not sure how your argument is working, though. The size of the baby boom would be mostly irrelevant, at a major numbers position. Unless you are arguing there is a saturation point for how many males a population can sustain, not a percentage that it can sustain. (You specifically claim ratio, though.)
Which is not to say I am trying to shoot it down. I'm very interested in exploring the question. My strongest suspicion is that there is something else we were putting people in contact with. Would be amusing if it was DDT levels or some such that we know is bad for other reasons and stopped completely.
That said, I fully acknowledge this as a bias of mine. That I suspect it is not the direct things people think they did that caused something to improve, but something else that happened to happen at the same time. Lead is attractive because we know it is terrible for you.