Why are shootings down? The answer may lie in gun violence interventions begun in the pandemic.

When President Joe Biden and Vice President Kamala Harris took office in January 2021, they did so on the heels of the largest single-year increase in murders on record. The national murder rate rose by about 30% in 2020, the last year of the Trump administration. Almost 5,000 more Americans were killed that year than in the year before, and the number of fatal shootings had almost doubled in cities including Milwaukee, New York, and Fresno, Calif.

Fast-forward almost four years. Unless something changes drastically in the next couple of months, Biden will leave office on the heels of the largest single-year decline in the murder rate on record.

Data gathered by Jeff Asher, a crime analyst, suggest that the national murder rate is on course to fall by roughly 16% in 2024, which would be the largest year-to-year drop since reliable statistics were first collected in 1960. Gun violence is falling rapidly in a large majority of U.S. cities, including Philadelphia, where the number of fatal shootings has dropped by more than 40% through August of this year.

If the current pace continues, at least 5,000 fewer Americans will be murdered this year than in 2020, Donald Trump’s last year in office. Based on historical data on the national murder rate, that would make 2024 one of the safest years in the history of the United States.

It is usually a mistake to attribute trends in violence to the presidential administration in power, or even to the actions of the federal government. Gun laws and carceral policy are almost entirely enacted at the state level, and policing is even more decentralized. And yet, there is good reason to think the sharp fall of violence under Biden is not coincidental.

The last year of the Trump administration was, in a word, chaotic. No presidential administration could have fully prepared for the pandemic in 2020, but the United States was the only nation where the pandemic led to a sharp increase in gun violence. Americans purchased more new guns in 2020 than in any previous year on record, and Trump left office with the highest murder rate of the 21st century. In Philadelphia, fatal shootings rose by more than 50% in Trump’s last year in office.

But things didn’t improve immediately when Biden took office. Data from federal background checks tell us that a similar number of Americans bought guns in 2021 as in 2020. State and city governments continued to face enormous challenges with depleted resources and staff, and the problems of 2020 did not disappear with the transfer of power to Biden. The murder rate remained high in 2021, with no immediate signs of a return to the relative peace of the Obama years.

The shift in policy began with the passage of the American Rescue Plan in 2021. The federal funding enabled cities and towns to avoid further slashing their budgets and cutting city services and staff. Biden resisted the calls to extract funding from law enforcement, and the administration advocated core reforms of policing while also investing billions of dollars to retain, hire, and provide new support to police officers. Powerful evidence from the 1990s and the Great Recession of the late 2000s tells us that this kind of influx of federal funding to states, local governments, and police departments generates clear reductions in violent crime.

The American Rescue Plan also directed funding to community violence intervention, a marked shift from previous federal policy that stands on sound evidence. The best research available tells us that community organizations can have powerful effects on violence and that the proliferation of local nonprofits during the 1990s played a central, underappreciated role in contributing to the drop in violence that took place across U.S. cities soon after.

The passage of the Bipartisan Safer Communities Act in 2022 reinserted the federal government into the regulation of guns. The law included new measures to crack down on gun trafficking, enhanced regulations for gun dealers, and enacted stricter regulations on purchases for Americans under 21.

The administration announced its intention to go further, establishing the White House Office of Gun Violence Prevention under the direction of Harris and proposing policies, like nearly universal background checks, that have been carried out at the state level and been shown to be effective in reducing gun deaths.

The Biden-Harris model for confronting violence has its flaws, and it is incomplete. The administration has called for, but hasn’t adopted, many of the basic regulations of firearms that have the strongest evidence behind them.

Federal funding directed toward community violence interventions was historic, but it was a drop in the bucket compared with the funding police units received from the pandemic relief bill. And the effort to fundamentally reform the institution of law enforcement is, at best, incomplete. The number of Americans killed by police departments each year has risen, not fallen, since Biden took office.

Despite these shortcomings, if one looks back over the past four years, some hopeful conclusions emerge. The federal government can help solve some of our grand challenges. Investments in public institutions and community organizations can save thousands of lives. Social policy enacted at the federal level can begin to transform our nation’s cities.

It is difficult to predict what will happen in the next four years under President Harris or President Trump. But we can say this: All the evidence available suggests that a federal approach characterized by the deregulation of guns and disinvestment in communities is likely to lead to higher levels of violence.

The most effective way for the federal government to reduce violence even further is to invest in new approaches to law enforcement, support community organizations, fund state and local governments, and keep guns out of America’s neighborhoods.

Patrick Sharkey is the William S. Tod Professor of Sociology and Public Affairs at Princeton and the author of “Uneasy Peace: The Great Crime Decline, the Renewal of City Life, and the Next War on Violence.”