content: Violent crime dropped everywhere, precipitously. One unexpected link has been leaded fuel. It started being phased out in the US in the mid 70s. Inhalation of lead emissions has been connected to lower IQ, increased aggression, and all other sorts of fun things. It's also not just a spurious correlation since different areas/countries, all with radically different circumstances, phased out leaded fuel at different times and saw similar effects on similar time frames. The effect and link is even present in countries where leaded fuel was phased out in different areas at different times. The evidence is extremely strong for this. Googling for 'lead crime hypothesis' will give countless credible results for more information. And something worth considering - just about every politician in congress tod  287c  ay spent their formative years breathing in a constant supply of lead fumes.