Specifically, looking at some of this data it would seem that understanding that causes of the increased crime rates would help guide us to an explanation for the subsequent decline.
http://en.wikipedia.org/wiki/Crime_in_the_United_States#Crime_over_time
Do the explanations for the crime rate rise correlate with the theories of the later decline?
Piggybacking a bit, but has the definition of crime changed and could it influence statistics?