CNN reports mass shootings based on data from the GVA, a nonprofit organization that tracks gun violence in the United States. CNN and the GVA define a mass shooting as a shooting that injured or killed four or more people, not including the shooter. The number of mass shootings and casualties is not exact and subject to change as reports from law enforcement, media and other sources GVA relies upon are updated and verified.

These charts include US mass shootings to date that fall under this definition and are updated as soon as new data is available from GVA. Data may lag behind breaking news reporting.