> The decline in crime since the early 1990s is actually a major area of study for criminologists, because there is no easy explanation for it. All categories h

> The decline in crime since the early 1990s is actually a major area of study for criminologists, because there is no easy explanation for it. All categories have decline, however they are measured, and in 30 years the field has not come up with an explanation that can account for all the observed facts. Counterpoint: https://en.wikipedia.org/wiki/Lead%E2%80%93crime_hypothesis https://en.wikipedia.org/wiki/Lead%E2%80%93crime_hypothesis https://www.motherjones.com/environment/2016/02/lead-exposure-gasoline-crime-increase-children-health/ https://www.motherjones.com/environment/2016/02/lead-exposur... The lead-crime hypothesis has the advantage over many other theories that it explains the global drop in crime, not just that in a particular nation or municipality.