How do Everytown and Mother Jones define mass shootings and how do their counts differ from GVA and the FBI?
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Executive summary
Everytown defines mass shootings by a high fatality threshold—four or more people killed in a single incident—and counts only events that meet that fatality bar, while Mother Jones focuses on indiscriminate public massacres, excludes conventionally motivated crimes (gangs, robberies, many domestic incidents), and has shifted its casualty threshold over time to match federal "mass killing" language (three or more fatalities) [1] [2] [3]. Those choices produce dramatically different tallies from the Gun Violence Archive (GVA), which counts any incident with four or more people shot (injured or killed), and from FBI data streams that were never intended as a direct "mass shooting" counter and use different constructs such as "mass murder" or limited reporting systems [4] [5].
1. Definitions at the core: Everytown’s fatality-focused standard
Everytown for Gun Safety adopts a fatalities-driven definition—events in which four or more people are killed, excluding the shooter—which aligns with how some major outlets and researchers frame a mass killing and narrows the set of incidents flagged as mass shootings to the deadliest events [6] [7]. Everytown’s intent is explicit: by using a high fatality cutoff the organization emphasizes the most lethal public massacres rather than including incidents with fewer deaths or primarily nonfatal injuries [8].
2. Mother Jones: a curated, motive-sensitive database
Mother Jones compiles an open-source database designed to capture “indiscriminate rampages in public places,” expressly excluding shootings that stem from conventional criminal motives such as gang violence, robberies, or many domestic disputes; it used a four-fatality threshold historically but adjusted to follow congressional “mass killing” language (three or more fatalities) in later practice and documentation [1] [9] [3]. The editorial choice reflects Mother Jones’ stated goal of isolating a particular phenomenon—rampage-style public attacks—rather than cataloguing all multiple-victim shootings [1].
3. Gun Violence Archive and the injury‑inclusive approach
GVA deliberately takes a broader, injury-inclusive stance: it labels as “mass shootings” any incident in which four or more people are shot (injured or killed), not excluding events on the basis of motive or setting, and it collects incidents in near-real time from media and law enforcement sources [4]. That numeric and methodologic openness produces much larger annual counts than Everytown or Mother Jones because incidents with many nonfatal victims—and those linked to crime or gang activity—are included [10].
4. The FBI’s role—and why its numbers don’t map cleanly
The FBI does not maintain a user-facing, up-to-date national “mass shooting” counter; instead it reports constructs like “mass murder” (four or more killed) and publishes specialized studies such as Active Shooter reports with distinct scopes and data collection limits, meaning FBI outputs are not directly comparable to activist or journalistic datasets without careful harmonization [4] [2]. Academic comparisons have repeatedly found that FBI administrative data (Supplementary Homicide Report, Active Shooter Report) will miss incidents recorded by crowd-sourced or press-based projects and reflect different inclusion rules and reporting lags [5] [11].
5. The practical effect: wildly different counts and partial overlap
Empirical comparisons show the divergence: when researchers applied Everytown’s “four or more killed” standard across databases for a single year, Mother Jones recorded as few as five matching incidents while GVA produced up to 24 for that same definition applied to its data feeds, and studies have reported GVA counts far higher (e.g., hundreds of multi-victim shootings in some years) versus Mother Jones’ far smaller, curated list—only a handful of events overlap across all databases and omission patterns reflect differing thresholds, motives exclusions, and data sources [12] [8] [10]. Peer-reviewed work and reviews in The Lancet and RAND emphasize that these methodological choices—not a single correct number—drive the variance, meaning “how one defines a mass shooting determines how many occur” [11] [6].