More interestingly, we also have cross-national natural experiments, where different countries banned lead gasoline at different times, and the timing of drops

More interestingly, we also have cross-national natural experiments, where different countries banned lead gasoline at different times, and the timing of drops in the crime rate is pretty spot-on https://www.motherjones.com/kevin-drum/2013/08/murder-rate-down-40-jamaica/ https://www.motherjones.com/kevin-drum/2013/08/murder-rate-d...