This article begins by describing trends and patterns of gun ownership and transactions in the population at large. The discussion is informed in part by another in this volume that reports the results of a new national survey (Azrael et al. 2017). This information sets the stage for an inquiry into the underground gun market, because the transactions that supply offenders involve guns that have at some point been diverted from the general commerce in guns. In particular, the guns that end up being used in crime, with few exceptions, were legally manufactured or imported and first sold at retail by a licensed dealer. (In this respect, the underground gun market is closer to the underground market for Vicodin than, say, the market for heroin.) The notable population-level trends are the decline in the prevalence of gun ownership, coupled with the “deepening” of ownership by those who do keep guns. The shift has been remarkable in the predominant motivation for buying and owning guns, from sporting uses to self-defense, as reflected by the types of firearms that are most popular (a shift from rifles and shotguns to handguns), by the overall decline in hunting, and by the near disappearance in the old rural-urban differences in gun ownership once one controls for other things.
Next, we review the social costs of gun misuse. The quest to reduce these costs is the ultimate motivation for our inquiry into underground markets. We acknowledge that guns provide a source of recreation or sense of security to millions of Americans and are sometimes instrumental in self-defense against criminal assault. But like so many useful commodities—motor vehicles, pharmaceuticals, pesticides—guns also cause extensive damage. For that reason, the design, distribution and uses of guns are widely regulated. Gun availability does not “cause” violence but does intensify it in the sense that when a gun rather than a knife is used in a violent encounter, the result is to greatly increase the chance that the victim will die rather than receive a nonfatal injury. Guns also give assailants the power to kill many people quickly, or to attack police and public officials. In neighborhoods where gun violence is concentrated, residents live in fear. The burden can be measured in terms of deleterious effects on public safety, health, economic development, and quality of life generally.
What can be done to reduce these burdens, and in particular to separate guns from violence? All levels of government regulate gun transactions, possession, and use. These regulations draw the line between legal and illegal gun transactions by imposing restrictions on weapon design, licensing of sellers, defining who is qualified to buy and possess, and mandating record keeping and reporting. To the extent that regulations have the effect of banning potentially profitable transactions, evasion becomes an attractive possibility. Thus the underground market is defined and motivated by regulation and partially undercuts regulatory effectiveness.
Turning to the heart of the matter, we next describe the underground gun market and assess the potential for additional regulation (or stronger enforcement of existing regulations) to reduce availability of guns to offenders. We report evidence suggesting that in some respects the underground market is sensitive to regulation. For example, when Virginia adopted a one gun per month maximum on handgun sales to any one customer, that state’s prominence as a “source” state in trafficking to Massachusetts and other states with relatively stringent regulations dropped sharply (see Braga 2017). But the market tends to be quite adaptable, and it cannot be taken for granted that a regulation that distorts trafficking patterns achieves the ultimate goal of depriving dangerous people of guns.
A survey of promising results helps connect those dots. Several articles in this volume provide new descriptive information that helps us better understand the channels by which guns are diverted into the underground market (Wintemute 2017; Collins et al. 2017). Daniel Webster and his colleagues provide an impact evaluation of an important new set of regulations in Maryland; Melissa Barragan and her colleagues report survey results relevant to ascertaining whether ammunition regulations are likely to be effective (Barragan et al. 2017; Webster et al. 2017).