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Twenty years after Columbine, the United States is still looking for how to stop mass public shootings. The rest of the world, where mass public shootings are actually much more common, is also looking for solutions. Russia, France, Finland, and Norway are among the European countries that have experienced far more deaths per capita from these attacks.

Change is coming, if slowly, in the United States. Twenty states currently allow teachers and staff to carry guns to varying degrees on school property. Florida’s just enacted law expanding their program.

Texas’ Senate overwhelmingly passed a measure by a 20-to-11 margin that removes the cap on the number of school personnel that can carry firearms at schools. The bill heads to Governor Greg Abbott’s desk, and he is certain to sign it into law.

It isn’t by coincidence that every mass public shooting in Europe since at least 1990 has occurred in an area where general, law-abiding citizens are banned from carrying firearms for protection, and for recent mass public shootings in New Zealand, Brazil, and the Netherlands. That has also held true for 98% of such attacks in the US since 1950.

Moms Demand Action, a gun control advocacy group funded by Michael Bloomberg, argues that the bill in Texas “would make school a much more dangerous place for our children.” By contrast, President Trump keeps proposing arming teachers and staff at schools, saying: “I’m telling you that would work.”

But with so many states having teachers and staff carrying guns, we don’t need to guess about how safe these schools are. Some states have had these rules for decades. The Crime Prevention Research Center, of which I am the president, has just released a new report looking at all the school shootings of any type in the United States from 2000 through 2018.

During these years, Utah, New Hampshire, Rhode Island, and parts of Oregon allowed all permitted teachers and staff to carry, without any additional training requirements. Other states leave it to the discretion of the local superintendent or school board. As of December 2018, more than 30 percent of Texas school districts let teachers/staff have guns. And in September 2018, Ohio teachers were carrying in over 200 school districts.

Carrying in a school is no different than in a grocery store, movie theater, or restaurant. Seventeen million Americans have concealed handgun permits — which is 8.5 percent of the adult population outside of permit-unfriendly California and New York. Nobody knows whether the person next to them might have a gun, unless it happens to be needed.

We found 306 cases of gunshots on school property, 48 of which were suicides. Not counting suicides, 193 people died and 267 were injured in these incidents. Four cases were simply instances of accidental gunshots by police officers.

The rate of shootings and people killed by them has increased significantly since 2000. The yearly average number of people who died between 2001 and 2008 versus 2009 and 2018 has doubled (regardless of whether one excludes gang fights and suicides).

This increase has occurred entirely among schools that don’t let teachers carry guns. Outside of suicides or gang violence in the wee hours of the morning, there has yet to be a single case of someone being wounded or killed from a shooting at a school during school hours. Indeed, the one shooting occurred at 2:20 AM in a parking lot when no armed teachers would have been around.

There haven't been any serious accidents. No student has ever got a hold of their teacher’s gun, and the one accidental discharge by a teacher occurred outside of school hours. The teacher had only very minor injuries.

School insurance premiums haven‘t risen at all from teachers being allowed to carry. “From what I’ve seen in Utah, [school insurance] rates have not gone up because of guns being allowed,” says Curt Oda, former president of the Utah Association of Independent Insurance Agents. Nor has a survey of six other states shown any increase in insurance costs.

Police have a very difficult job stopping mass public shootings, as they will be the first people targeted in an attack. Concealed carry means that killers won't know who is armed. Even if they take an officer by surprise, they must worry that they are revealing their position to someone else who can stop them.

Gun control groups may paint fearful pictures of what might go wrong with teachers carrying, but that fear gets harder to push given these programs’ successes. This research provides evidence that armed teachers deter attacks. It is past time for us to do something that really works. Let’s stop leaving our schoolchildren as sitting ducks.

* Lott is the president of the Crime Prevention Research Center.