The recent shootings in Monterey Park and Half Moon Bay, California, both carried out by senior Asian men using semiautomatic handguns, have prompted questions about whether a mass shooting contagion effect is getting stronger.
Mass shootings have become more frequent and deadly in recent years, with the majority of the deadliest mass public shootings in the United States happening since 2010. The USA TODAY mass killing database shows that 2019 and 2022 saw the most mass killings and mass shootings on record, while the Gun Violence Archive recorded the most mass shootings in 2021 and the most mass murders in 2022. Assuming a contagion effect exists, an increase in mass shootings could lead to a vicious cycle in which more shootings lead to more shootings. However, it’s unclear whether the contagion effect itself is getting stronger or whether there is simply a higher baseline of shootings due to factors such as economic conditions, changes to gun laws, or the number of guns in circulation.