Mass shootings increased considerably in the U.S. following the expiration of the assault weapons ban.
The ban, which prohibited civilians from purchasing semiautomatic rifles and magazines accommodating more than 10 rounds of ammunition, was enacted on Sept. 13, 1994, and remained in place until Sept. 13, 2004, when Congress let it expire. According to Mother Jones, which keeps a database of mass shootings resulting in three or more fatalities dating back to 1982, there were 15 mass shootings resulting in 96 deaths during the ban, compared to 35 mass shootings resulting in 299 deaths in the following decade. Since then, there have been 58 mass shootings resulting in 483 deaths.
In the decade prior to the ban, there were 16 mass shootings resulting in 125 deaths.
The Conversation noted that it is difficult to determine the exact impact of the ban expiring on the spike in mass shootings given additional factors, including "changes in domestic violence rates, political extremism, psychiatric illness, firearm availability and a surge in sales, and the recent rise in hate groups."