With data for 171 countries, Lankford found that the United States had by far the most public mass shooters, with 90 during the 46-year period. That’s five times as many as the next country on the list—the Philippines, with 18. Rounding out the top five were Russia (15), Yemen (11) and France (10). In other words, although the U.S. accounts for less than five percent of the world’s population, it had 31 percent of mass shootings between 1966 and 2012.
The strongest statistically significant factor Lankford found was the national firearm ownership rate. “What was surprising was how strong the relationship was—no matter what test I ran the data always showed the same thing,” he says. Even when Lankford removed the American outlier, his statistical tests showed just as strong a relationship between firearm ownership rates and mass shootings.
The top five countries in terms of civilian firearm ownership rates—the U.S., Yemen, Switzerland, Finland and Serbia—each made the top 15 in the list of mass shootings. This finding “suggests that essentially you can’t be in the top five in firearm ownership and not have this problem,” Lankford says, even in countries like Switzerland and Finland, which are “relatively peaceful in terms of total number of homicides.” Homicide and suicide rates did not appear to be significant in Lankford’s study
But moving away from guns, there's a cultural component:
“At least one explanation” about violence in the U.S. has suggested that “crime and deviance occur when there’s an unhealthy gap between people’s dreams and aspirations and their ability to reach those dreams,” Lankford explains. In the U.S. in particular, he writes, success and fame are idolized. “Everybody is shaped by culture in a way,” says Lankford. “Our culture has people reaching for the stars and slipping and falling probably more often.”
Public mass shooters—who often make comments or leave behind notes that help explain their motives—frequently cite “blocked goal achievement (such as being expelled from school or fired from work)” or “negative social interactions (such as being bullied by fellow students, coworkers, or supervisors),” according to the paper. Mental illness can distort certain individuals’ perceptions of such strains and exacerbate their inability to deal with them in a non-violent manner.
That school and work represent these grievances as well as the gap between one’s aspirations and ability to fulfill those dreams could explain why American mass shooters are more likely than those in other countries to target schools and workplaces.
So to sum up, the United States is a culture that places high value on material and personal achievement, as well as fame, ridicules failure, promises success and doesn't deliver, romanticizes violence and has wide access to guns.