New York City is a May Issue area for concealed carry. In Chicago, and all of Illinois, concealed carry is prohibited. So I guess that Morgan agrees that concealed carry reduces violent crime.
Philadelphia used to lead the country in gun related murders until they fixed the situation. Philadelphia changed the way they collect the statistics, they found that if they separated all the shootings that were committed by juveniles, listed them separately and refused to release those statistics, the murder rate was reduced significantly. The reason is that the gangs had figured out that if a juvenile committed the murder, he would get out in a year or two with a sealed record, so the gangs were assigning most of the killing to younger members.