The numbers were dropping long before the current wave of marijuana decriminalization.

Decriminalization of property crime probably helps too.

Marijuana and Tobacco are not cool anymore for kids. Part of the reason why Vaping became a fad is because the youngsters did not bother with all kinds of smoking.

The numbers show that teenage drinking and smoking has been going down year on year since the 90s. Vaping changed at but I think that trend is a short lived too.

It's not just or even mostly the direct "kid smoked weed went to jail". It's growing up in a culture of drug war were the police are the enemy cause they round up, hassle, and jail your older brothers, parents, everyone you know for doing things you know are not criminal. The pushers, gangs, lookouts, mules, etc. Surround kids with crimes and criminals, they will pick up the lifestyle.

Pot is not a gateway drug. But pot illegalization was a gateway into crime.

Also decriminalization of being born to an immigrant.

Wow, since when was that illegal? That's like the entire country at this point.