Gunfire erupted in my city on Thursday night, at the intersection of 14th and Riggs streets NW. For those unfamiliar with Washington, 14th Street serves as the main commercial artery for some of the city’s densest neighborhoods, and Riggs crosses its most affluent stretch. When the shooting started around 8 p.m., the intersection was filled with people out for dinner.

This follows last Saturday’s gunfight outside Nationals Park, while a game was in progress. These events may be high-profile because of their proximity to the privileged, but they are in fact part of a horrific surge in gun violence and homicides. Murders rose nearly 20 percent above their pre-pandemic level last summer. Those numbers are basically unchanged this summer, even as the city reopens.

We can’t afford the false comfort of irrelevant comparisons to the early 1990s, when crime was at its peak. Nor should we be cheered that other kinds of crime are down, since many of those acts, such as burglary or muggings, are hard to commit when many people are parked at home. A number of U.S. cities are at risk of entering a vicious cycle whereby crime begets more crime. That chases out jobs and residents, begetting still more crime. Mayors must act decisively before that happens.

Whatever the root causes of crime, its prevalence is at least partly a function of the likelihood of a person being caught and punished for any particular crime. Unfortunately, the likelihood that a criminal will be caught and punished is also at least partly a function of the amount of crime.

Imagine, if you will, two cities with roughly the same laws, identically sized police departments and similarly skilled investigators. Now, imagine the crime rate in City A is three times the crime rate of City B. It is immediately obvious that perpetrators operating in City B will face a much higher risk of getting caught than people committing the same crimes in City A, because police in City B have lower caseloads and can pay more attention to each investigation.

If you were a criminal, you’d probably rather operate in City A. Maybe you face a little more competition from fellow criminals, but you face a much lower risk of going to jail.

For that reason, a higher crime rate makes further crimes even more likely — the aforementioned vicious circle. Conversely, lowering the crime rate can create a virtuous cycle in which committing crime becomes less attractive.

Those vicious or virtuous cycles can be further exacerbated by other factors. When crime is high, people may not even bother telling the police; when I was growing up in New York City, few people bothered reporting crimes unless they involved grievous bodily harm or needed to be claimed on insurance. Deprived of information about the community, police become even less effective.

Non-criminals also fear crime and will go to great lengths to avoid it, such as staying home or moving. All else equal, City A, with its high crime rate, is more likely to end up with abandoned houses, empty storefronts and deserted streets — a much more attractive place to commit crimes than a street bustling with residents and shoppers. City A will also probably have a faltering tax base, which will make it harder for government to reverse these trends, whether that’s through more police or higher social spending.

That was the disaster visited on U.S. cities by the late-20th-century crime wave. That’s the disaster that should be at the forefront of mayoral minds as they contemplate what to do about murderers menacing their streets.

The high-profile shootings in highly public spots matter not because they are more important when they threaten the affluent, but because such events are more likely to chase people away from the city’s commercial destinations. That, in turn, makes violence more likely in the future.

They can also matter if they serve as a wake-up call to Mayor Muriel E. Bowser (D). Crime needs to be the city’s No. 1 priority until the homicide rate starts falling again, because the longer that vicious circle is allowed to spin, the harder it becomes to check that momentum.

That, of course, doesn’t mean going back to the excesses of 1990s-era policing, many of which were morally wrong, constitutionally dubious and alienating to the community, breeding the backlash of the past seven years. But it does mean that the mayor should rethink shrinking the police department’s budget at a time when the department is already smaller than it has been in decades.

The kinds of alternative strategies that Democrats, including our mayor, like to talk up — from housing supports to pilot programs to assisting recently released inmates — may help. But in the short term, there is no substitute for police on the street to deter crime and track down any offenders. And if we don’t take care of the short term, we’ll find it much harder to handle the long run.

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