Almost all US mass shooters since 1966 have four things in common:

Those four things are: childhood trauma, a personal crisis, examples that validate their feelings, and access to a firearm

Oh, scientists, you have such a grasp of the obvious. Without your study, who could have guessed that those who committed firearm violence had access to a firearm? It is worth noting, however, that the vast majority used legally obtained firearms that they purchased themselves or took from others in their household. More than half of all mass shooters in the database purchased their firearms personally and legally.

There are two key trends:

Hate is on the rise

There has been a significant increase in shooters motivated by racism, religious hate, and misogyny since the 1960s, especially in the last five years.

• • There were 75 mass shootings between 1966 and 2000, of which only 13 were hate-inspired. That’s about one hate-inspired mass shooting per 32 months.
  • By comparison, of 32 mass shootings that happened in the US since 2015, 17 were hate-inspired, or about one every three to four months.

In other words, hate-inspired mass shootings (those driven by general racism, misogyny or religious zealotry, as opposed to personal grievances) occur about nine times more frequently in the past five years than they did at the end of the 20th century. There were more such incidents in just the past five years than in the last 35 years of the 20th century.

A desire for fame is also on the rise

The percentage of shooters driven by a desire for fame has also risen substantially in the last five years, the study found. In the first 15 years of the 21st century, some 3% of perpetrators were motivated by the desire to go down in history as a mass shooter. Between 2015 and 2019, that number jumped to 12%.

One thing the study fails to mention: the other types of mass shootings, those not inspired by general hate or a desire for fame, have remained relatively constant at two per year. In the 1966-2000 period, there were 60 such shootings, rounding to two per year. In the last five years there have been 11 such shootings, also rounding to two per year. Using the precise frequency with the decimal points shows that they have actually gone up from 1.7 to 2.2 per year, but this increase is minimal compared to the vast increases in the other two categories, as seen below.

(% of change calculated from the actual frequency, not the rounded numbers shown above.)

In other words, while the frequency of mass shooting is almost exactly triple what it was in the 1966-2000 era (from 2.14 per year to 6.40), almost 90% of the increase (3.77 more incidents per year out of the overall 4.26 increase) can be attributed to crimes inspired by fame or hate.