[DugwayDuke]

"But Donohue argues that such comparisons are generally skewed, since the states that have adopted such laws tend to be rural and relatively isolated from the types of violent crime -- such as offenses related to crack cocaine -- that disproportionately affect more urbanized states, many of which have not enacted similar laws."

You could have pointed out the obvious, it's rather doubtful that crack dealers apply for Concealed Carry Permits. Therefore, this factoid is utterly and completely irrelevent.

[traditionalist]

The fact is relevent because if you were not aware of it, it could induce as spurious relationship between crime and concealed carry laws. States without concealed carry (CC) more likely to have a log drug-related crime. Hence if you examined the relationship between CC and crime without controling for crack addiction, you would that CC tends reduce crime even though it may not. This is called correlated omitted variable bias.