This is one of the ploys anti's use to argue for more strict gun control laws in the "lax" border states of such cities. They argue that these states need to have much tough gun control laws in order to stem the tide of "illegal" guns making their way into cities such as Washington, DC, New York Chicago, etc. In fact, the revserse should be instituted: relax the gun control laws within the cities and watch things change quickly.
One of the cheapest things that can be done to lower crime is to make firearms more available to citizens and to carry this several steps further by instituting carry permit laws and even open carry. This costs a city or state very little in comparison with other measures which have been tried to reduce crime.