This is the latest accepted revision, reviewed on 11 January 2019. Total deaths in US mass shootings from 1982 to 2017, according to Mother Jones. Locations of US mass shootings in 2015, according to Mass shootings PDF Tracker.
There is no fixed definition of a mass shooting, but a common definition is an act of violence—excluding gang killings, domestic violence, or terrorist acts sponsored by an organization—in which a gunman kills at least four victims. The United States has had more mass shootings than any other country. There is no fixed definition of a mass shooting in the United States. The Investigative Assistance for Violent Crimes Act of 2012, signed into law by Congress in January 2013, defines a « mass killing » as one resulting in at least 3 victims, excluding the perpetrator.
Memorial at the Welcome to Fabulous Las Vegas sign following the 2017 Las Vegas shooting, which resulted in 59 deaths and 851 non-fatal injuries. Studies indicate that the rate at which public mass shootings occur has tripled since 2011. Between 1982 and 2011, a mass shooting occurred roughly once every 200 days. However, between 2011 and 2014 that rate has accelerated greatly with at least one mass shooting occurring every 64 days in the United States. The decrease in firearm homicides has been attributed to better policing, a better economy and environmental factors such as the removal of lead from gasoline.