Why have public mass shootings become more deadly?

• Published date: 01 February 2020
• DOI: http://doi.org/10.1111/1745-9133.12472
• Author: Adam Lankford,James Silver
• Date: 01 February 2020

DOI: 10.1111/1745-9133.12472

SPECIAL ISSUE ARTICLE

COUNTERING MASS VIOLENCE IN THE UNITED STATES

Why have public mass shootings become more

deadly?

Assessing how perpetrators’ motives and methods have changed

over time

Adam Lankford1James Silver2

1The University of Alabama

2Worcester State University

Correspondence

AdamLankford, Department of Criminology &

Criminal Justice, The Universityof Alabama,

P.O.Box 870320, Tuscaloosa,AL 35487-0320.

Email:Adam.Lankford@ua.edu

Research Summary: Public mass shootings in the United

States have become substantially more deadly over time.

We document this increase, offer a model to explain it,

review supporting evidence for the model, and present new

findings on offenders from 1966 to 2019. It appears that

societal changes have led to more public mass shooters

who are motivated to kill large numbers of victims forfame

or attention, as well as to more shooters who have been

directly influenced by previous attackers. Theyof ten spend

extended time planning their attacks and are increasingly

likely to acquire powerful weapons and develop specific

strategies to enhance their lethality.

Policy Implications: New policies should be aimed at

addressing the aforementioned factors. For instance, the

deadliest public mass shooters’ desires for fame and atten-

tion might be countered by a change in media coveragepoli-

cies. Additionally, the deadliest perpetrators’ lengthy plan-

ning periods have been associated with more warning signs

being reported to police, so that type of information could

justify denying many potential attackers access to firearms

through extreme risk protection orders and red flag laws.

KEYWORDS

fame-seeking, firearms, high-fatality incidents, lethality, public mass

shootings

Criminology & Public Policy. 2020;19:37–60. wileyonlinelibrary.com/journal/capp © 2019 American Society of Criminology 37

38 LANKFORD AND SILVER

In 2016, the number of people shot by public mass shooters in the United States reached a 40-year

high, and in 2017, the number of people killed by active shooters surpassed any year since the FBI

began recording data (Duwe, 2017; Hayes, 2017). Public “mass” and “active”shooters refer to a single

offender type; the most significant difference is that “mass” shootings are traditionally defined as inci-

dents that result in four or more victim deaths, whereas “active” shootings have no minimum (Fox &

Levin, 2015). Notably, these increases do not seem primarily attributable to population growth: They

exist even when victimization figures are adjusted per capita (Duwe, 2017).

There has also been a marked rise in high-fatality attacks of this type. At the extreme, although the

United States has experienced public mass shootings for more than 50 years,the five deadliest incidents

in national history have all occurred since 2007 (Ahmed, 2018). During this span, the tragic “record”

for number of victims killed in an American mass shooting has been set (at Virginia Tech where 32

victims died), broken (at the Orlando Pulse nightclub where 49 victims died), and then set again (on

the Las Vegas strip where 58 victims died).1

This disturbing trend seems counterintuitive. After all, there are many reasons why today’s mass

shootings should theoretically be less deadly than those from prior decades. Since the 1999 Columbine

school shooting, there has been a sustained and dedicated effort to improve how law enforcement

officers, medical personnel, and ordinary civilians respond to active and mass shootings (Blair, Nichols,

Burns, & Curnutt, 2013; Pons et al., 2015). This priority area has received more funding, training, and

public outreach than ever before (Blair et al., 2013; U.S.Depar tment of Justice, 2017). And there have

been continued advancements in life-savingmedical technology and techniques to help first responders

and emergency room surgeons keep more shooting victims from perishing than in the past (Belluz,

2017; Smith & Delaney, 2013).

To date, no one has provided a clear and compelling explanation forwhy public mass shootings have

become deadlier over time. That may be because finding evidence-based answers is so challenging.

Similar struggles are often encountered in other areas, such as scholars’ attempts to explain changes

in crime rates, climate patterns, or financial markets. Because the path of history provides a sample

size of only one reality, it is challenging to know what may have occurred if different variables were

present.

In this article, we offer an explanation for why public mass shootings have become more deadly by

identifying several keychanges in American society and then providing evidence of their corresponding

effects on the behavior of some shooters. First, however, we will briefly review the empirical evidence

that a quantifiable change has indeed occurred.

1INCREASED LETHALITY OF PUBLIC MASS SHOOTINGS

To analyze changes in public mass shootings over time, we drew data from a publicly available list

of qualifying incidents (N=165) compiled by Berkowitz, Lu, and Alcantara (2019). According to

the definition they used, public mass shootings must involve a firearm and result in at least four or

more victims being killed.2Past attack locations for these incidents have included schools, colleges,

workplaces, public businesses, government buildings, military facilities, and other popular locations.

Shootings that arose from gang conflict or robberies or that took place exclusively in private homes

were not included. The list compiled by Berkowitz et al. (2019) comprises both cases documented in

prior scholarship—especially from Duwe (2007)—and news reports, and it was designed to capture

all incidents from 1966 to present. The starting point of 1966 is widely recognized as the first year of

modern mass shootings (with the University of Texas Tower attack); as an ending point, we obtained

complete data through August 30, 2019 (which was our last opportunity to update our findings).