I actually feel that time will tell us the answer to this question.

Because back in the far past (like over 100 years ago) nd thorough reporting on crime was present in some places but non-existent in others.

Nowdays most regions keep track of their crime rate in some type of way. Some pleaces dont keep track of exactly what crimes are committed but they simply report that 'XYZ and ABC persons committed a crime together on so-and-so date . Other places not only keep track of the type of crime committed bu t also of the chosen gender, traumatic childhood experiences, height , ethnicity, and weight of ALL the caught offenders

So if in 60 years when the populations decreases substantially if we see that the reported and convicted crime rate per 1000 people has declined on most parts of the world then we can conclude that one of the reasons could be closer knit communities.

However the only way we could definitely determine if lower crime rate correlates with closely knit communities then we would have to ask those who were caught committing a crime now and in the future what motivated them to commit that crime AND we would have to ask those who testified to wanting to commit a crime whythey didnt commit that crime. And if one of the major reasons given then and now centre around 'having close friends who helped me out financially when I was down on my luck' , 'or being part of a community that diverted my desire' , or 'not wamting to paint my community or my loved ones as despicable' , or things like that then we could definitely prove that the two correlate.