How many mass shootings might have been prevented by stronger gun laws?

After each mass shooting in America, ​lawmakers debate a familiar menu of gun control polices. Yet no major reforms have passed Congress since 1994 — and the killings continue. On Wednesday, for instance, multiple people were shot dead at the Molson Coors corporate complex in Milwaukee. The killer’s motives and methods are still unclear.

A new database from The Violence Project provides some insight into the history of mass shooting and what measures, if any, could affect them. ​Researchers there conducted a detailed study of 167 mass shootings resulting in 1,202 deaths that have occurred in the U.S. since 1966.

We’ve cross-referenced their data with five types ​of gun​ control ​proposals. The analysis reveals that if all of these policies had been in effect at the federal level, ​they would have ​had the potential to ​prevent 146 out of 167 shootings, including all but one shooting in the past five years.

Odessa, Texas

Aug. 31, 2019

Austin, Texas

Aug. 1, 1966

Austin, Texas · Aug. 1, 1966

Odessa, Texas · Aug. 31, 2019

There is no guarantee that these laws would be effective in stopping motivated killers from ultimately achieving their goal. Also, some of the proposals are more recent and could not be expected to have stopped attacks in the distant past.

Here are five types of gun laws and which shootings they could have addressed.

Ban on straw purchases

Seeks to stop someone from buying a gun for someone else. Read more

The two shooters at Columbine High School​, both minors during the planning phase, had a​n older friend purchase a firearm for them at a gun show. A ban on straw purchases would ​have prevented that.

Columbine

April 20, 1999

13 dead

23 injured

Columbine

April 20, 1999

13 dead

23 injured

Safe storage requirement

F​irearms ​would have to be kept in a locked box ​when not in use. Read more

This law aims to prevent unauthorized people, like children, from accessing firearms. In 2001, an underage shooter in Sacramento ​who was blocked from purchasing a semiautomatic weapon was able to kill five people using his father’s firearms.

Sacramento

Sept. 8, 2001

5 dead

2 injured

Sacramento

Sept. 8, 2001

5 dead

2 injured

Assault weapons ban

​This would prohibit the sale of many high-powered rifles. Read more

After the 2012 shooting at Sandy Hook Elementary School in Connecticut, some members of Congress pushed to restore an assault weapons ban that had expired in 2004. The new ban would have included semiautomatic weapons that weren’t in the 1994 law, including the rifle used at Sandy Hook, but the effort failed.

Years when the federal assault weapons ban ​was ​in effect

Sandy Hook

Dec. 12, 2012

27 dead

1 injured

Years when the federal assault

weapons ban ​was ​in effect

Sandy Hook

Dec. 12, 2012

27 dead

1 injured

​Mandatory background checks

Unlicensed dealers would be required to vet ​prospective buyers with the FBI. Read more

Private sellers, such as those at gun shows, are not required to run a background check on purchasers. Even when background checks are required, they are often sloppy. That was the case in Charleston, S.C., where the shooter was able to purchase a firearm because a felony he committed had not been reported to the FBI.

Charleston church

June 17, 2015

9 dead

0 injured

Charleston church

June 17, 2015

9 dead

0 injured

Red flag law

Prohibits firearm access to someone who makes violent threats or is suicidal. Read more

​The ​man who killed 17 people at ​Marjory Stoneman Douglas High School in ​Parkland, Fla., had attempted suicide, and ​his threats to attack a school had been reported to the local sheriff. A red flag law could have given someone the opportunity to intervene.

Stoneman

Douglas

Dec. 12, 2017

27 dead

1 injured

Stoneman Douglas

Dec. 12, 2017

27 dead

1 injured

​You be the lawmaker. Try your hand at gun control

​See what might have happened if different policies, or combinations of policies, had been in effect since 1966.