Missouri once had one of the country’s strongest gun violence prevention measures: all handgun buyers had to go through a background check—in person, at a sheriff’s office—before receiving a gun permit. In 2007, however, that was repealed, and the legal age to carry a concealed gun was lowered to nineteen last year.

Research by Daniel Webster, the director of the Johns Hopkins Center for Gun Policy and Research, found that in the first six years after the state repealed the requirement for comprehensive background checks and purchase permits, the gun homicide rate was 16 percent higher than it was the six years before. During the same period, the national rate declined by 11 percent. After Professor Webster controlled for poverty and other factors that could influence the homicide rate, and took into account homicide rates in other states, the result was slightly higher, rising by 18 percent in Missouri,” writes The New York Times‘s Sabrina Tavernise.

Researchers caution that causation is difficult to prove, but most are convinced the data suggests an effect.

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