Mark — I agree that the number of guns that are registered in a certain area of D.C. does not necessarily indicate the total number of guns in that area (perhaps I should have titled my post “More Legal Guns, Fewer Legal Guns, Whatever”). I also agree that the D.C. registration process is unnecessarily burdensome, and even that this disproportionately affects the poor. However, it does not follow that the numbers tell us “nothing.”
The Heller decision made it legal to register guns in the District, and this, clearly, had an effect on behavior — some people who otherwise would not have owned guns bought them (or brought them in from out of state) and registered them. Meanwhile, the decision presumably had no effect on unregistered guns, which were illegal both before and after it. Therefore, the numbers tell us a whole lot about what the change in the law did — that is, which areas of the city now have more guns thanks to the court ruling. As it happens, there’s quite a debate going on about what we can achieve by changing gun laws, so I thought it worthy of mention that this new information — while hardly dispositive in itself — fits into a large body of evidence indicating that changes in gun-control laws do very little to affect crime either way.
Further, I’m not sure that “the proportion of law-abiding people with firearms is much higher in Anacostia than in Georgetown.” All the surveys I’ve seen indicate that if anything, gun owners tend to be whiter and wealthier than the general population, though the particular demographics of those two areas (lots of crime in Anacostia and very few hunters or Republicans in Georgetown) probably make a difference. Not to mention that owners of unregistered guns in Anacostia are, by definition, not “law-abiding.”