Something happened to the US in the late 60's early 70's. Until that point US homicide and incarceration rate was the same as the rest of the 1st world( aka the other 30 or so free democracies). Suddenly after that it spikes 400%. Within the decade the US homicide and incarceration rate has climbed to 4-5x higher than any other 1stt world country. And so it remains today.
This isnt a dig at the US. There must be a reason behind it since by and large other metrics between the free world countries stayed comparable.
