Data from big cities suggests most violent crime fell last year. It's not the full picture, experts say.

It's widely known the U.S. doesn't have reliable federal data on crime trends. But a new report out Thursday aims to provide a snapshot of what happened in dozens of the nation's largest cities last year.

Homicides and gun assaults in those cities fell in 2022. At the same time, robberies and property crimes rose, and motor vehicle thefts and carjackings continued to trend upward, according to the report from the Council on Criminal Justice.

It's the latest attempt by researchers and organizations to provide policymakers, law enforcement and the general public with information when issues of violent crime and criminal justice reform are at the center of U.S. discourse.

"There's this information void ... and we've attempted to fill that," said Rick Rosenfeld, lead report author and criminologist at the University of Missouri-St. Louis. "But it should not be the case that private entities are put in the position of having to meet this public need."

Researchers say that while the new report is helpful in indicating possible national trends, it has blindspots.

Homicides, murders fell in big cities

The report from the Council on Criminal Justice, a think tank with hundreds of members focused on criminal justice policy, analyzes police data on monthly crime rates for ten violent, property and drug offenses in 35 U.S. cities. It's the organization's tenth such report since it began issuing them in 2020.

The cities included in the study cover about 37 million residents and make their crime data available through online portals. Not every city reported data for each category.

The trends in 2022 are largely the inverse of what happened in the U.S. amid the height of the COVID-19 pandemic in 2020 and 2021, when violent crime rose and property crime decreased. According to the report, homicides fell about 4% in 2022, based on data from 27 of the 35 cities included in the study.

That finding is in step with data from other groups, such as the research firm AH Datalytics, which collects data on murders from police departments in nearly a hundred cities. The firm found murders rose in 2020 and 2021 but declined nearly 5% in 2022.

Jeff Asher, AH Datalytics co-founder who has been tracking the trends since 2015, also assessed 25 cities with available data and found shootings were down in 18 of the cities, with some seeing "substantial declines."

While the decline in murders and shootings is heartening, he said, the U.S. murder rate each year since 2020 has remained at elevated levels not seen since the 90s.

"The reality is there was really nowhere to go but down," said Christopher Herrmann, a former crime analyst for the New York Police Department and associate professor at the John Jay College of Criminal Justice in New York City

The report also found aggravated assaults, gun assaults, drug offenses, domestic violence incidents and residential burglaries all fell while robberies, nonresidential burglaries and larcenies rose, based on data from varying numbers of cities.

Motor vehicle thefts, carjacking continued to rise

Motor vehicle thefts and carjackings have been steadily rising for several years, the report found. Carjacking is the "theft or attempted theft of a motor vehicle by force or threat." It's technically a form of robbery. The report also found:

• Of 30 cities with data on motor vehicle thefts, 27 have seen a rise since the beginning of the pandemic.
• Motor vehicle thefts rose 21% in 2022 – up 59% from 2019, based on data from those cities.
• Vehicle thefts more than doubled in eight of those cities from 2019 to 2022.
• Based on data from seven cities, carjackings rose by 24% from 2020 to 2022. For context, motor vehicle thefts in those cities rose 54% during that time.

Despite the rise, carjackings aren't as common as Americans may assume, Rosenfeld said. Overall, motor vehicle theft rates are more than 20 times greater than the rates for carjackings, he said. 

The limitations of city crime data

While city-level analyses can provide helpful information, it's hard to extrapolate a singular national trend based on those types of studies, said Jorge Camacho, policy director of the Justice Collaboratory at Yale Law School.

"The experiences of the 15 largest cities or the 50 largest departments in the country is going to be very different than the other more than 17,000 municipalities that also have law enforcement departments," Camacho said. "If people want to understand crime trends, they should really look locally."

Even within municipalities, crime trends differ neighborhood by neighborhood – and sometimes block by block. That's part of why it's hard to conclusively say what's driving apparent national trends.

Crime is a "complicated social phenomenon" with many causes, said Jeffrey Butts, director of the Research and Evaluation Center at John Jay College of Criminal Justice in New York City. "Easy answers are popular, but they are never accurate," he said.

Dig deeper on crime data

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The 35 cities included in the report are: Atlanta; Aurora, Colorado; Austin, Texas; Baltimore; Boston; Buffalo, New York; Chandler, Arizona; Charlotte, North Carolina; Chicago; Cincinnati, Ohio; Dallas; Denver; Detroit; Houston; Jacksonville, Florida; Lincoln, Nebraska; Los Angeles; Louisville; Memphis; Milwaukee; Minneapolis; Nashville; New York; Norfolk, Virginia; Omaha; Philadelphia; Phoenix; Raleigh; Richmond, Virginia; Sacramento; San Francisco; Seattle; St. Louis; St. Petersburg, Florida; Washington, D.C.

What do you want to know about the U.S. criminal justice system? Reach out to reporter Grace Hauck on Twitter at @grace_hauck or email her at ghauck@usatoday.com.