A display case at a gun store in Bridgeton, Mo. (Jeff Roberson/Associated Press)

Firmin DeBrabander is an author and associate professor of philosophy at Maryland Institute College of Art.

It has been a bloody summer in Baltimore. July saw 45 people killed, the most murders in one month since August 1972.

The surge in violence has been as sudden as it has been dramatic: By the end of July, homicides were up 60 percent over the same period a year ago, from 118 to 189, and non-fatal shootings rose 83 percent, from 200 to 366. The victims have been predominantly African American.

No one is sure what is behind the surge in violence, which began with the protests after Freddie Gray died in April in police custody. Some speculate it is because of less aggressive policing in the wake of the controversy. Others agree with former police commissioner Anthony Batts, who noted that the riots — when dozens of pharmacies were looted — unleashed “enough narcotics on the streets of Baltimore to keep it intoxicated for a year,” spawning turf wars among rival gangs.

But Baltimore is not alone in its misery. The Baltimore Sun reported that “a rising number of homicides have been recorded in cities as different as Chicago (up 18 percent from last year), Milwaukee (up 117 percent) [and] Houston (up 36 percent).” In Washington, more than 100 people have died compared with 72 this time last year, or a 39 percent increase. Officials in these cities are equally confounded. However, there are two common threads: The victims are mostly African American, and the bloodshed is fueled by easy access to guns — illegal guns in particular.

The Black Lives Matter movement has brought deserved attention to police killings and mistreatment of African Americans. Beneath the well-known incidents that have galvanized the movement, however, there has been a steady slaughter in urban areas. This month, the 300 Men March from Baltimore to Washington sought to call attention to the carnage as African American neighborhoods try to find ways to reduce the violence.

The South Side of Chicago has been rocked by gun violence this year, too, and Police Chief Garry McCarthy says his officers have been confiscating illegal firearms in vast quantities — more than Los Angeles and New York combined. But it has not slowed the violence, because illegal guns are too easy to replace and punishment for having them, McCarthy complains, is too lax. “Possession of a loaded firearm, illegally, in the state of Illinois, is not even considered a violent crime for sentencing purposes,” he said, while New York imposes a mandatory 3½-year minimum sentence.

Gun rights advocates love to mock Chicago. The city has banned some semiautomatic weapons and high capacity magazines. It requires residents to report the transfer of firearms and to store weapons securely (with a trigger lock, or in a locked container) if there are children at home. After Chicago’s deadly Fourth of July weekend, the conservative Web site Infowars.com ran the headline “82 Shot, 15 Dead in the City with the Strictest Gun Laws in the United States.” For gun-rights supporters, Chicago is prime evidence that gun control laws do nothing to reduce gun violence, but “only restrict the law-abiding citizens” and turn them into prey, said Richard A. Pearson, executive director of the Illinois State Rifle Association.

And yet, how is Chicago, or any city, to carry out meaningful and effective gun control when surrounded by permissive jurisdictions and stymied by maddening loopholes — all by design of the gun rights movement and its chief lobby?

A study revealed that “sixty percent of guns recovered in crimes in Chicago were first sold in other states,” principally Wisconsin, Indiana and Mississippi, none of which require universal background checks for gun sales. The National Rifle Association has fought federal efforts to mandate universal background checks. Half of the remaining weapons in Chicago crimes were found to come from four area gun stores. But it is not easy disciplining these stores, or other errant firearms dealers, again thanks to NRA lobbying, which has ensured that the Bureau of Alcohol, Tobacco, Firearms and Explosives, the federal agency charged with stemming the flow of illegal guns, is depleted and hamstrung.

Maryland also has stringent gun laws: It has banned assault weapons and high-capacity magazines, and it requires background checks for handgun sales. But these laws do little to stem Baltimore’s violence so long as it remains easy to get guns from nearby states.

The nation requires a unified effort to control gun violence and stem the flow of illegal firearms. The NRA repeatedly blocks such efforts — and African Americans bear the brunt.

African American support for gun control has long been higher than support among whites. This is not surprising since African Americans are dying in vast numbers. The statistician Nate Silver highlighted race disparity again this summer when he pointed out that the murder rate for African Americans is nearly eight times that of whites — and comparable with murder rates in the developing world.

Law enforcement and the Black Lives Matter movement, at odds over a number of pressing issues, share common interest here. Neither can advance their stated missions — saving lives, affirming the value of all lives — amid a profusion of guns, which so easily waste lives. We must revive the effort, derailed after the Sandy Hook school massacre, to enact federal gun-control measures such as universal background checks, which most Americans support. Other democracies have committed to strong, uniform gun control — with success. It is obscene that we tolerate the carnage in our midst, especially when many effective fixes are available.