Homicides are falling across the U.S. And that shift could impact the role crime — often a top voter concern — plays as an issue in November’s election. 

But it is a phenomenon for which experts don’t have a clear explanation.

Some say homicide peaks come and go in cycles, some say policing improved after the COVID-19 pandemic, and some attribute it to the evolving national conversation about how to handle crime.

A data analysis released last week shows that the number of homicides in cities like Boston, Philadelphia, Washington, D.C., and Chicago, are dropping.

While many major cities, especially those run by Democrats with liberal-leaning policies and populations, have received backlash from Republicans for being inundated with violent crime, the new data paints a picture of an improving situation.

Experts, though, aren’t agreed on exactly why the number of homicides has fallen so far, so fast.

Boston saw the sharpest decline from 2023 to 2024, with homicides dropping by 82 percent. In Philadelphia, homicides dropped by 37 percent; in Dallas, homicides dropped by 27 percent; and in Chicago, homicides dropped by 6 percent, according to estimates from city police department reports compiled by AH Datalytics.

Jeffrey Fagan, professor of law and epidemiology at Columbia University, attributes the improvements to a typical crime cycle.

“I think there’s something natural in this cyclical nature of homicide and violence. One of the distinguishing features of what happened in the most recent period was that it had to do with murder more so than with other violent crimes. Other violent crimes rose but not nearly to the same extent as murder,” he said. “It’s likely to happen again, we just don’t understand the circumstances when these externalities will create the social and economic conditions for homicide rates to arise again.”

Fagan outlined other cycles, like in the 1960s when homicides started rising and peaked by 1972, then fell sharply. And in the late 1970s, when they took off again to peak in 1981 and then crash. And in the late 1980s, homicide rates skyrocketed and peaked in 1991 before crashing again.

“So, what’s the common denominator other than the fact that there’s this recurring cycle of peaks, crashes, peaks, crashes, peaks, crashes? There’s something natural about these episodes in that they follow an epidemic pattern. Any epidemiologist will tell you that it looks like any other disease epidemic,” he said.

Alex Piquero, former director of the Bureau of Justice Statistics under President Biden, outlined the factors he argues caused the spike in homicides: Community prevention programs were put on hold during the COVID-19 pandemic, and law enforcement pulled back due to the 2020 murder of George Floyd by a Minneapolis police officer and because of pandemic staffing issues.

Piquero, a professor of sociology and criminology at the University of Miami, said those conditions have been reset. “Their staffing levels are going up, police are around the community more, they’re targeting violent places and violent people using appropriate statistical methodology.”

Piquero looks at crime as a local level issue and noted it’s hard to tell yet if the funding from the Department of Justice (DOJ) under the Biden administration to combat crime is helping. 

Fagan agreed, noting that homicides peak or crash “regardless of what criminal justice or public health policies are in place.”

Andrea Headley, a criminal justice policy expert at Georgetown University’s McCourt School of Public Policy, argued that investments from the federal government, whether from the bipartisan gun safety act or the American Rescue Plan, have made an impact.

Biden signed the American Rescue Plan into law in 2021, and it provided $10 billion for public safety. The bipartisan gun safety law was signed in 2022, enhancing background checks for purchasers younger than 21 and funding red flag laws to keep guns out of the hands of people deemed to be a threat to themselves or others.

“We see funding for law enforcement that happened,” Headley said. “We see, which I think probably is arguably more important, is the funding and the support structures for community violence interventions, wraparound social support services, but also the investments in job programs and mentoring. Things that we know typically are correlates of violent crime. And, kind of this targeted approach of taking money from the federal level and investing it in local communities.”

She noted the holistic approach isn’t new, but the national conversation about it is new — it was launched when the federal government provided that support.

“I think that kind of wraparound strategy of, we’re investing in community safety from all of these angles and in a way that is unprecedented is really powerful in terms of what we’ve been seeing with some of the declines, particularly last year,” she said.

The data comes in an election year, when crime is top of mind for many Americans. Both the Biden and Trump’s campaigns have blamed the other for previous spikes in crime.

The Biden camp argues that the president stands with law enforcement, including billions in funding, while Trump has called for federal law enforcement agencies to be defunded.

“By standing with law enforcement and against Republican officials’ efforts to defund the police, Joe Biden reversed the spike in violent crime he inherited from his predecessor and delivered the lowest crime rates in almost 50 years,” White House spokesperson Andrew Bates said.

Trump, meanwhile, called for the U.S. to “get back to law and order” and said something with crime prevention is “not working” after attending the funeral last month of New York police officer Jonathan Diller, who was killed on duty. The Trump campaign did not respond to a request for comment on the dropping homicide rate.

Republicans have also equated crime with Biden’s immigration policies, especially after the killing earlier this year of Georgia student Laken Riley.

Experts, though, push back on that notion.

“It is established that immigrants do not commit more crime than native born Americans, period, period, period, period, that’s been replicated over and over again,” Piquero said.

Republicans also often use Washington as an example of a city with violent crime, pointing to stories of carjackings or other crimes. 

Washington last year had its highest number of homicides since 1997 and double the amount of carjackings compared to a year prior. In new data from D.C. police, homicides are down by 27 percent in the nation’s capital compared to this time last year.

Headley said the slower pace of improvements in D.C. could be attributed to the unique structure of the city, considering it is not a state and has a disjointed government structure.

“In terms of why, we could speculate about why the decline hasn’t been as quick or sharp compared to other cities, I think D.C. is unique because of the way in which there’s different levels of jurisdictions,” she said.

Fagan added that the city has extremes of wealth and poverty “that create susceptibility to conflict and violence.”

Another argument about crime is the economy, and if the economy is improving, the crime rate will improve. Biden has worked to combat inflation and seen improvements in his polling about his handling of the economy.

Experts, though, push back on that concept, too.

“That argument doesn’t hold across crime types. If a great economy leads to lower crime, that doesn’t affect the kid who put up a gun and he’s 14 years old and [couldn’t] care less about a job,” said Piquero. “So, a lot of crime is very unplanned, it’s situational.”