According to the UCR, murders in the United States rose by 8.6 percent in 2016, a notable increase even before it’s placed alongside the 10.8 percent jump in 2015. Homicide data is considered the most reliable of the indicators measured by the UCR, because it tends to be more easily measurable by local law-enforcement agencies. Other offenses like rape and aggravated assault saw a slightly smaller increase, while property crimes remained roughly the same. (Auto theft, which rose 7.4 percent, was a notable outlier.)

Rural, urban, and suburban communities all saw increases in violent crimes in 2016. But they were of varying degrees. Some places, like Houston and Washington, D.C., saw the number of murders either stay roughly the same or slightly decline. Other communities fared worse. Chicago ended 2016 with 762 murders, a whopping 58 percent jump over 2015’s total. Baltimore experienced its second-deadliest year on record with 358 murders, surpassing the previous record set in 2015.

That disparity could be felt in the national stats. John Pfaff, a Fordham University law professor who studies crime statistics, noted on Twitter that 22 percent of the nationwide increase in murders came from Chicago alone. But inside Chicago itself, 50 percent of the homicide rise came from just five neighborhoods, which account for only 9 percent of the city’s overall population. Those neighborhoods, in effect, account for 10 percent of the national increase in murders.

In an email, Pfaff pointed out that Monday’s data matched what scholars already knew. “Crime has always been highly localized,” Pfaff said. “Studies in several cities have shown that about half of all reported crime occurs in under 10 percent of all city blocks, and almost all crime in under half. And those ‘at risk’ blocks remain fairly constant over time. So talking about crime in ‘the U.S.,’ or ‘Illinois,’ or even ‘Chicago’ has always been somewhat misleading.”

New York City’s declining crime rates also highlight the geographic incongruity in crime spikes. The city’s struggle with violent crime in the late 1980s and early 1990s made it synonymous with the nationwide crime wave of that era. Its homicide rate peaked at 2,245 murders in 1990; by comparison, its rate dropped to 335 murders in 2016. Shootings dropped by 12 percent as other major crimes fell across the board. City officials attributed the decrease to a crackdown on violent gangs, although New York City Police Department data reported only 40 percent of murder cases had resulted in an arrest.

What’s driving the increases in violence in the affected cities isn’t clear. Researchers in Chicago have struggled to find any direct causal factors behind the jump in gun violence there. Shootings and murders noticeably rose around the time that the Chicago Police Department released a video of officers killing 17-year-old Laquan McDonald in November 2015, but it’s uncertain if a subsequent drop in police street searches played a role. (Whether it would is also debatable: New York City defied predictions after its crime levels continued to drop after it all but abandoned stop-and-frisk in 2011.) And what exactly causes crime to rise and fall is far from certain: Scholars have plenty of theories but no conclusive explanations for the widespread crime decline of the 1990s.