I'm thinking in terms of population and both are very low compared to other cities. I'll ask the question I asked pmv- looking internally at cities that have strict gun laws and access from other areas to firearms, why is there such variation between cities?
I'd love to see some well written analysis of historical comparisons between cities over time over the last century until now. I know of no such work that is of academic quality.
I would have to research the difference in gun laws between NYC and Lansing although I suspect New York's are considerably tougher. That being said, one of the problems with gun laws in the US is that they only apply in the state they're in and it's super easy to transport guns across state lines as you mention.
As for the rest I don't have too many good answers, my gut says that the greater economic opportunities offered in NYC vs. various rust belt towns probably makes it less likely for people to become involved in crime generally, and then shootings specifically.