In our federalist nation, regulation in 50 capitals makes a huge difference.
In 2007, Missouri’s legislature repealed an 86-year-old law requiring all gun purchasers to first obtain a permit after a background check by the local sheriff’s office. The federal government requires background checks on all purchases from federally licensed dealers, but Missouri’s “permit to purchase” law supplemented federal requirements by mandating a more rigorous background check by local law enforcement for all sales.
In the months and years that followed, sales of handguns rose quickly throughout the state. The percentage of suicides carried out with a gun, a common proxy for gun ownership rates, rose by 24%. Firearm homicides increased by 20% in the years following the law’s repeal, while non-gun homicides stayed the same, suggesting the rise was directly caused by easier access to guns. The gap in the homicide rate between White and Black residents widened, along with gun assaults among law enforcement in urban centers such as Kansas City and St. Louis. Despite the rise of gun violence in the wake of this reform, Missouri would go on to adopt a series of other deregulatory measures, including an attempt to nullify federal firearms regulations, lowering the age to carry a concealed firearm to 19 and making it legal to carry a concealed firearm without a permit.
What transpired in Missouri reflects a broader trend between state policy, the prevalence of guns and the problem of gun violence. Despite the challenge of accessing high-quality data on the supply of guns, a growing body of evidence makes it clear that state policy has a strong impact on the sales, accessibility and usage of guns, and the prevalence of guns is linked directly with the prevalence of gun deaths. This literature sheds light on states that have made major progress in regulating the free circulation of guns, but it also illuminates several challenges states face in attempting to confront gun violence.
As three researchers who have each contributed to the gun control policy literature, we view state reforms as a key lens through which America’s gun supply problems are best understood. States not only dictate the local gun market conditions within their own jurisdiction but also influence gun markets in other states operating under different policy regimes.
Federalism and the patchwork of gun laws
Though the interpretation of the Second Amendment describes the limits of what courts will consider constitutionally permissible at any given time, the American system of federalism gives states wide discretion to set their own firearm policies, resulting in a patchwork of gun laws that vary dramatically by jurisdiction. The federal government sets a floor — such as licensing dealers, regulating interstate sales, banning certain types of guns and barring certain individuals from owning guns — above which states can enact stricter laws, so long as they’re deemed constitutional. Hence, it’s states (and sometimes cities) that do most of the regulatory work by setting rules around gun carrying, strengthening penalties for gun crimes and deciding whether to go further than federal standards regarding who can own a gun and what their rights are.
While federal policies such as the Brady Handgun Violence Prevention Act regulate firearm sales among licensed dealers, private handgun sales outside of these settings — an estimated 40% of the total gun sales annually — fall squarely within the jurisdiction of each state. In 2023, only 20 states required some form of background check among private firearm sales, and even fewer involved a permitting process to purchase a firearm. State regulations of private firearm sales also shape local gun availability, since many gun owners purchase firearms through secondary markets.
The more regulations a state adopted, the more gun deaths were averted.
In recent years, state firearm policies have moved in opposing directions. Many Republican-led states have eliminated permit requirements for carrying firearms, rolled back existing regulations and blocked local governments from passing stricter laws. Meanwhile, Democratic-led states have expanded background checks, banned assault weapons and high-capacity magazines and broadened red flag laws.
Courts have played an increasingly active role in shaping this landscape. Since the U.S. Supreme Court’s Bruen decision in 2022, lower courts have been required to assess gun laws based on historical analogs, leading to legal uncertainty around policies like assault weapon bans, waiting periods and public carry restrictions. The result is a fragmented and polarized policy environment in which access to guns and the risks they pose depend heavily on where one lives. Yes, guns are mobile — and many of them travel from states with weak regulations to states with stronger ones. But state laws have very powerful local effects.
The Missouri case illustrates how making state gun regulations more lenient can have lasting effects on gun supply, public safety and racial inequality. Research from two of the authors of this piece (Sharkey and Kang) investigates the other side of this equation, that is, what happens when states pass more restrictive gun policies?
When researching this question, we found a consistent pattern: The more regulations a state adopted, the more gun deaths were averted. Background checks and waiting periods were especially effective. In 2016 alone, we estimated the cumulative effect of stronger laws in 40 states to have prevented more than 4,200 deaths, about 11% of the total gun deaths for that year. California accounted for the largest share of lives saved, followed by New York and Florida. In contrast, six states that weakened their laws saw an estimated 111 additional gun deaths in that same year, with nearly half of them in Missouri, where regulations had steadily eroded.
These findings provide strong evidence that the accumulation of restrictive state laws can make a meaningful difference in reducing gun deaths, and additional evidence suggests broader effects on related outcomes like police shootings. Previous research finds a strong link between gun availability and fatal encounters with police, including cases involving unarmed individuals. This suggests police behavior changes in areas with high levels of circulating guns, and reducing fatal police shootings will require more than just reforming policing — it also means addressing the widespread availability of guns.
Private handgun sales — an estimated 40% of the total gun sales annually — fall squarely within the jurisdiction of each state.
Three Key Challenges
There are three key challenges to overcome when turning to state gun laws to prevent gun violence.
The first is the most obvious: As the political winds shift, many states have reversed course and weakened state-level gun regulations. Since 2016, many states loosened their laws, some voluntarily, others in response to Supreme Court rulings.
Strong evidence suggests this is not a coincidence. One of us (Williams) examined the consequences of Missouri’s 2007 repeal of a state law requiring background checks and permits for handgun purchases. The impact was severe, and it was felt most acutely among Black residents of the state’s major cities. In St. Louis and Kansas City, firearm homicides among Black residents jumped by 17 per 100,000 people in the aftermath of the repeal, and non-gun homicides fell slightly by almost 4 per 100,000 people.
A second challenge is that more restrictive gun laws do not necessarily have an immediate impact on gun deaths — potentially due to the existing stock of firearms already in circulation — and in some cases may lead to a surge in gun purchases. Research on the rollout of the Brady Act, for example, found no evidence of an impact on firearm homicides, but did identify a selective effect in reducing firearm suicides among older Americans.
Additionally, high-profile events shifting expectations concerning future gun control and market forces can be important in accounting for the increased proliferation of firearms. For example, one study shows that fears of a stricter gun control policy regime under a potential Obama administration leading up to the 2008 U.S. presidential election resulted in sharp increases in nationwide gun demand. Using data from futures markets, the author shows that as markets provided stronger indications of then-U.S. Sen. Barack Obama winning the presidential election, gun demand rose by nearly 4.5%. Notably, these effects are strongest in states with weaker gun laws.
Porous state borders mean what happens in one state affects those around them.
A strand of research over the past two decades has shown how incidents like mass shootings, the election of pro-gun control politicians or pending changes in state regulations can lead to spikes in gun and ammunition sales amid anticipation of new restrictions. Gun purchases soared in the aftermath of the 2013 Sandy Hook shooting, for instance, leading to an increase in gun deaths that was most pronounced in the states with the largest increase in gun sales following the horrific mass shooting. More recently, a group of researchers studied how residents of Oregon responded to a 2022 public referendum providing voters the choice to strengthen gun control throughout the state. They found that background checks rose by 14% before the referendum and then by more than 150% after it was passed. The long-term impact of the new regulations may well reduce the prevalence of guns in Oregon, but in the short-term, the state is clearly seeing a surge of gun sales.
A third challenge arises from the flow of illegal firearms across state borders. It’s common in America for guns to flow from states with weaker laws to gun markets in states with more rigorous policies. A 2013 paper finds strong evidence that being exposed to nearby states with weaker gun laws increased criminal gun possession. States such as California, Illinois and New York, which possess some of the strongest gun laws in the country, often suffer from considerable gun trafficking due to this phenomenon.
In a previous Vital City contribution, one of us (Williams) argues that a surge in postpandemic gun sales among nearby states with weaker gun laws could present enormous public safety challenges to the state of New York. Commonly referred to as the “Iron Pipeline,” these states — including Florida, Georgia, North Carolina, Pennsylvania, South Carolina, Virginia and in some cases Ohio — accounted for 40% of crime recoveries throughout the state in 2021 and 80% of crime gun supply in New York City alone. Thus, even when states adopt stringent measures to regulate the proliferation of firearms, they must also contend with market forces imposed on them by states with weaker gun control policy regimes. Porous state borders mean what happens in one state affects those around them, and gun violence in states with strict regulations cannot be effectively addressed through local policy alone.
Why States Matter
What happens when states repeal gun regulations or enact laws that make guns more accessible? The three of us have studied this question from several angles — across states, within states and within communities. The bottom line is the same: State gun laws matter. While recent federal legislation such as the Bipartisan Safer Communities Act provides much-needed reforms, such as enhanced background checks for gun buyers under the age of 21, these changes will do little to curb the flow of illegal guns from primary to secondary gun markets. Coordinated legislative efforts within and across states will be required in order to better oversee both private gun sales and gun trafficking within and across states. Achieving this coordination, however, requires moving beyond our current patchwork approach to something more systematic.
Sociologist and technology policy expert Alondra Nelson offers a framework for this shift in what she calls policy innovation through governance. Nelson distinguishes between reactive “regulation” and proactive “governance”; the latter shapes the conditions under which technology develops rather than just responding to harms after they occur. Applied to firearms, governance means not just reacting to gun violence after it occurs, but proactively shaping the conditions under which firearms circulate in society. Gun rights advocates often promote the false choice between public safety and constitutional rights, when effective governance can achieve both.
We would be remiss not to offer some of the lowest-hanging fruit in addressing the proliferation of firearms: having access to better data. Despite our best efforts to study these problems using survey questions and other proxies for gun ownership, we often know very little about legal gun owners and only have access to very crude snapshots of interstate gun trafficking. While restrictions such as the Tiahrt Amendments — which determine how firearm data collected by the ATF can be used and shared — severely limit access to the gun trafficking data, studies leveraging local gun permit data or gun trace data via academic-government partnerships have provided fascinating insights into gun proliferation and its effects on gun violence. Future opportunities to leverage similar data could prove to be equally rewarding in our efforts to inform evidence-based gun control policy.