The overwhelming majority of illegally owned guns you'll find somewhere like Chicago, NYC or Boston are stolen. The reason they come from places like Indiana,

The overwhelming majority of illegally owned guns you'll find somewhere like Chicago, NYC or Boston are stolen. The reason they come from places like Indiana, Pennsylvania or New Hampshire is basic economics. There is no market there since guns are so readily available legally. Even if you're a prohibited person a straw purchase is much more accessible and less of a liability to all involved than a stolen gun so the market for stolen guns moves to wherever straw purchases are much less practical. Because guns are more available legally you get a much broader cross section of society owning them which means more get stolen. Supply and demand works is magic and they all wind up over the border where they can be sold.