State Firearm Laws and Interstate Transfer of Guns in the USA, 2006–2016

Abstract

In a cross-sectional, panel study, we examined the relationship between state firearm laws and the extent of interstate transfer of guns, as measured by the percentage of crime guns recovered in a state and traced to an in-state source (as opposed to guns recovered in a state and traced to an out-of-state source). We used 2006-2016 data on state firearm laws obtained from a search of selected state statutes and 2006-2016 crime gun trace data from the Bureau of Alcohol, Tobacco, Firearms, and Explosives. We examined the relationship between state firearm laws and interstate transfer of guns using annual data from all 50 states during the period 2006-2016 and employing a two-way fixed effects model. The primary outcome variable was the percentage of crime guns recovered in a state that could be traced to an original point of purchase within that state as opposed to another state. The main exposure variables were eight specific state firearm laws pertaining to dealer licensing, sales restrictions, background checks, registration, prohibitors for firearm purchase, and straw purchase of guns. Four laws were independently associated with a significantly lower percentage of in-state guns: a waiting period for handgun purchase, permits required for firearm purchase, prohibition of firearm possession by people convicted of a violent misdemeanor, and a requirement for relinquishment of firearms when a person becomes disqualified from owning them. States with a higher number of gun laws had a lower percentage of traced guns to in-state dealers, with each increase of one in the total number of laws associated with a decrease of 1.6 percentage points in the proportion of recovered guns that were traced to an in-state as opposed to an out-of-state source. Based on an examination of the movement patterns of guns across states, the overall observed pattern of gun flow was out of states with weak gun laws and into states with strong gun laws. These findings indicate that certain state firearm laws are associated with a lower percentage of recovered crime guns being traced to an in-state source, suggesting reduced access to guns in states with those laws.

Network analysis of firearm movement among US states

“…This is consistent with studies examining pairs of states that showed the differential in rearm laws between source and destination states correlated with the movement of rearms between the two states, such that rearms are more likely to move from states with weaker laws to states with stricter laws (9, 13). Similarly, a study of 25 US cities found that cities in states with mandatory registration and licensing systems had a higher proportion of crime-related rearms originating from other states (8), and that states with higher number of rearm laws had a higher percentage of crime-related rearms originating from other states (11).…”

“…Following other studies (1,11,15), the independent variable was the rearm law strength score, an unweighted count of state-level rearm laws, with higher scores denoting more laws regulating rearms and fewer laws deregulating rearms (e.g. law providing blanket immunity to rearm manufacturers).…”

Network analysis of firearm movement among US states

“…Following other studies (1,11,15), the independent variable was the rearm law strength score, an unweighted count of state-level rearm laws. This variable was obtained from the State Firearm Laws Database, which compiles data on state-level laws in all 50 states since 1991 and codes them into fourteen categories of laws that regulate and deregulate rearms (16).…”

“…For example, the implementation of a law limiting handgun purchases in Virginia resulted in a lower proportion of crimerelated rearms recovered in the entire Northeast region that were traced to Virginia (10). States with more stringent rearm laws in general have a higher proportion of crime-related rearms originating from outside the state (8,11), of which a large proportion are from states with weaker rearm laws (12). For pairs of states, increasing rearm law stringency in the source state was associated with reduced movement of rearms between two states, while increasing stringency in the destination state lead to increased movement (9,13).…”

Differences in public support for handgun purchaser licensing

“…Licensing laws require prospective handgun purchasers to apply to state or local law enforcement, typically in-person and with fingerprinting of applicants, and undergo a thorough background check before obtaining a license. Licensing laws are associated with reductions in guns diverted for criminal use,4–6 firearm homicide7–9 and firearm suicide 10 11…”