Murders in the U.S. rose nearly 9% last year, and one-third of that increase came from just a few neighborhoods in Chicago, according to a Wall Street Journal analysis of the FBI’s annual 2016 publication, Crime in the United States.
While violent crime (homicide, rape, assault, and robbery) also rose nationwide from 2015 to 2016 — over 4% — the data show the increase was not uniform, but rather concentrated in cities like Chicago and Baltimore. 
Los Angeles and Washington, D.C., meanwhile, saw “meaningful declines in violence [that] have been sustained since the 1990s.”
Interestingly, the paper’s neighborhood-by-neighborhood analysis claimed that areas where homicides spiked had a “lighter street presence by police following officers’ high-profile killings of young black men.” 
A Pew Research Center poll from January 2017 showed that an overwhelming number of police officers say widespread protests following high-profile killings of black suspects have made police less willing to conduct basic police work, such as stopping and questioning suspicious people in high-crime neighborhoods, and using an appropriate level of force to diffuse a situation.
In Baltimore, violent crime rates were going down until 2015, when police officers “pulled back from a more proactive approach” following widespread city riots after the death of Freddie Gray, a 25-year-old black man who suffered a severe spinal injury while being transported in a police van on April 1, 2015, and died one week later.
Gray had a long criminal record and was arrested for possession of an illegal knife after running from a bike patrol officer who made eye contact with him. State Attorney Marilyn Mosby filed charges against the six officers involved. Each officer was either acquitted or had charges dropped.
Violence in Baltimore has stayed historically high following the riots, with arrests plummeting, shootings soaring, and the police force itself getting smaller.
In Chicago last year, homicides jumped to 771, 58% higher than in 2015, and more than the number of murders in Los Angeles and New York combined. Half of that increase, the analysis showed, came from just five neighborhoods, and is largely attributable to gang warfare. In a “roughly four-mile radius of West Garfield Park,” for example, there are at least 30 gangs.
In 2015, David Weisburg, a George Mason University criminologist, released a study that established the “law of crime concentration,” which states that a disproportionate amount of any city’s violent crime occurs in a small geographic area of the city.
Weisburg found that in large cities, 50% of crime occurs on just 4% to 6% of a city’s streets, while 0.8% to 1.6% of streets produce one-quarter of all crime.
In Chicago, as in Baltimore, police became less proactive following protests against the fatal 2014 shooting of a black teenager, Laquan McDonald, by a white police officer, Jason Van Dyke, who has been charged with first-degree murder.
A FiveThirtyEight analysis found that in Chicago and other cities with high-profile deaths of black men involving police officers, a “pullback in policing was accompanied by a sharp increase in gun violence.”