Trends in the Lethality of American Violence

Abstract

Research on homicide trends has not adequately considered trends in interpersonal disputes. Aggregate homicide rates partly reflect the extent to which less serious forms of interpersonal violence escalate to deadly violence. This study argues that the rate of disputes in a society and the proportion that result in deadly violence vary independently. But both are necessary to understand lethality trends. The study compares rates of homicide in the Supplemental Homicide Report with rates of violence in the National Crime Victimization Survey to estimate lethality trends from 1992 to 2016. Findings are discussed regarding their implications for explanations of homicide trends.

Keywords

homicide violence lethality victimization social psychology

Unforeseen and sharp reversals of the downward trajectory in contemporary homicide trends have reignited scholarly interest in the factors responsible for changes in aggregate rates over time. Once again, the usual questions appear: Why did rates of killings increase after years of steady declining? Was the sudden rise disproportionally felt among certain population subgroups? Are trends in homicide indicative of more general patterns in criminal violence? A satisfactory answer to these and other critical questions likely will not be found in a single variable, whether an exogenous shock or otherwise.

Before embarking on the quest for a theoretical explanation, perhaps it is useful to reframe the way researchers traditionally think about aggregate homicide rates. Crime trends research borrows heavily from macro-level theories of institutional performance and cultural organization (Rosenfeld & Messner, 2013), but has all but ignored the literature on the social psychology of aggression. This literature may provide a powerful interpretive lens through which to conceive of explanations for aggregate homicide rates.

Most criminal homicides are a byproduct of less serious, more frequent incidents of interpersonal conflict (Luckenbill, 1977). Social psychological perspectives on aggression argue that motives, propensities, and situational conditions determine when everyday conflicts are likely to result in violence. Versus end in mere words (see Berg & Felson, 2016). Moreover, the frequency of disputes and the extent to which they escalate to deadly encounters vary over time and among population subgroups. A theme of this study asserts that the volume of disputes in any society, and the proportion of those that result in deadly violence, can vary independently. I argue that important sources of such variation possibly rest in distal social organizational and cultaral conditions, which operate to reduce or increase the situational opportunities and motivations for deadly conflicts. Moreover, the availability of lethal technology may partly determine the frequency of serious disputes, as well as trends in the proportion of those that culminate as killings.

Upon close inspection, the social psychological literature, therefore, suggests a search for the causes of homicide trends may benefit by shifting the focus to rates of dispute escalation. Because homicide rates are indicative of societal trends in lethal escalation, regardless of the frequency of interpersonal conflicts, it is necessary to account for variation in lethality. Such an approach requires researchers to study the macro-level conditions that influence rates of lethal escalation separate from the incidence of serious disputes. Crime trends researchers must then explain why some societies, places, or social groups experience high levels of violence but not homicide. Until now, this puzzle has received limited attention.

The goal of this study is to apply the general assumptions from social psychological perspectives on aggression to assess recent trends in lethality rates. For the purposes of this analysis, nonlethal forms of violent victimization are treated as proxies for interpersonal disputes. The study relies on more than two decades of disaggregated data from the National Crime Victimization Survey (NCVS) and the Supplemental Homicide Report (SHR) series to compare yearly estimates of nonlethal victimization rates—serious disputes and robberies—to homicide rates among individuals aged 12 and older. In addition, the study focuses on changes in lethality from 2014 to 2016 to better understand the spike in homicide rates. The results are discussed in terms of their implications for knowledge about the contours and sources of American violent crime trends and for future theory testing.

Background

No single theory of violence holds a consensus of interest among scholars of crime who study aggregate trends. Few established macro-level perspectives apply specifically to explanations of criminal violence; they are intended to explain criminal behavior generally, whether property offenses, homicide, or public order crimes. Moreover, the explanatory scope of most perspectives is restricted to violent behaviors defined as illegal, which is why it is instructive to consult theories of aggression, which happen to be found at lower analytical units, to obtain insights about the processes that combine into aggregate rates.

One micro-level social interactionist perspective on aggression relies on social psychological principles to understand how everyday disputes develop and why they escalate to violent episodes (see Berg & Felson, 2016; Pruitt & Rubin, 1986; Tedeschi, Smith, & Brown, 1974). This perspective conceives of violent behavior as a social influence tactic or an instrumental goal-oriented action. It views the use of violence as related to basic human desires such as fairness, security, and status attainment. A large fraction of violent events, but certainly not all, are thought to be instrumental and done in the service of acquiring material and abstract goals. According to this perspective, actors engage in violent behavior to pursue three motives (Tedeschi & Felson, 1994). First, they do so to rectify perceived or real transgressions and to obtain retribution. For instance, disputants will punish opponents when they blame them for negative outcomes (Black, 1983). Second, they are motivated by desires to force compliance or to deter people from behaving in a certain manner. For instance, studies find that physical coercion is more likely in disputes when nonviolent methods of social influence prove ineffective (Deutsch & Krauss, 1962). Third, violence is intended to promote or preserve a desired social identity (Pruitt & Rubin, 1986).

Dispute-related violence often results from reactions to perceived wrongdoing. Central to the development of most, but not all, disputes are grievances—or beliefs, often expressed as accusations, that “another social agent has performed an unfair action . . . a norm violating action” (Tedeschi & Nesler, 1993, p. 13). Grievances stem from a limitless number of issues, including poor role performance, mistakes, obnoxious behaviors, and rule violations. Unlike the case with interpersonal disputes, physical force and harm are incidental to predatory actions. For instance, most robbery offenders use violence strategically to force victim compliance. But robbery is not a straightforward act of predation. Sometimes grievances arise during robberies, transforming them into disputes (Tedeschi & Felson, 1994). At times, robbery is perpetrated as a form of retribution for perceived wrongdoing (Wright & Decker, 1997). Acts of victim resistance can be interpreted by the offender as transgressions deserving of moralistic punishment. Thus, robbery can involve a mixture of dispute and predatory concerns.¹

Dispute Escalation

People seldom express their grievances or seek redress; most fade away with memory. Some disputes lead to verbal aggression, a small number result in physical violence, and just a fraction end as deadly altercations. Disputants are not necessarily motivated to engage in violence at the beginning of the encounter but may eventually become motivated by the actions of the other party. It is critical to study the processes unfolding in the situation to understand how conflicts end. Provocations such as insults, criticisms, threats, and nondiplomatic reproaches all generally increase risk of escalation (Tedeschi & Felson, 1994; Tedeschi et al., 1974). These actions cast disputants into unfavorable identities, creating additional grievances (Cody & McLaughlin, 1988). Sometimes threats are used to force compliance from the target, but threats can also be provocative and can backfire, resulting in retaliatory counterattacks (Pruitt & Rubin, 1986; Schelling, 1980). In addition, disputes are likely to escalate to violence when adversaries enlist third-party partisans for support.

Disputes rarely escalate to aggressive confrontations because individuals take steps to address the concerns of the grievant even when they do not believe their complaints are legitimate. For example, a person accused of wrongful behavior will often engage in “remedial actions” (e.g., accounts, apologies; see Berg & Felson, 2016; Luckenbill, 1977) in which they demonstrate deference, remove blame, or accept responsibility for their offensive behavior. More often than not, the intent of these actions is to avoid punishment from the aggrieved party.

Because disputes can be just as dangerous for offenders as for potential victims, people must consider their relative “coercive power” when deciding whether to provoke a physical confrontation (Tedeschi et al., 1974). If a person is unable to avoid a powerful adversary, they may do something to increase their relative power (Benard, Berg, & Mize, 2017). Some actors secure partisan allies, whereas others will enhance their own physical strength. But perhaps no form of manipulatable power has more of an influence on the way everyday disputes unfold than lethal weaponry. Most of all, firearms enable weaker offenders to reduce the tactical advantage held by an adversary. Firearm use may also increase the immediate risk of serious injury in hostile encounters because of what is known as an “instrumentality effect”: Not only are guns more lethal, but they also require less effort to deploy than most other weapons (e.g., Cook, 2013). The efficiency of firearms may also encourage individuals to attack more powerful adversaries than they would otherwise confront. In addition, the use of firearms can encourage an arms race in which individuals arm themselves when they believe potential adversaries are also armed (Cook & Ludwig, 2004). Although disputants often deploy firearms to achieve goals other than harm (e.g., instill fear), research on the outcomes of robberies and assaults has shown that, regardless of intent, guns are more lethal than other weapons (see Cook, 2013; Wells & Horney, 2002). Similarly, situational studies have found that guns significantly increase the likelihood of conflict escalation (Phillips & Maume, 2007).² A comparison of multiple nations found that aggregate variation in homicide and gun violence rates was much greater than variation in unarmed violence (Felson, Berg, & Rogers, 2014; Zimring & Hawkins, 1999). These results suggest that a country’s homicide rate reflects, to a large extent, the tendency of its offenders to use firearms. Thus, to understand aggregate trends in lethal violence, researchers should study the nature of violent incidents in a society rather than the mere frequency.

Macro-Level Social Conditions and Lethality

Social psychological models reveal the importance of temporal patterns of lethality, and not simply the frequency of nonlethal violence, for understanding national homicide trends. Disputes and homicides are conceptually distinct, but the latter generally emerge from the former, which is a challenge for criminological theories to explain at the aggregate level. How can macro-level criminological theory be used to predict lethality trends from the perspective of social psychological research? Next, I briefly speculate on some good possibilities.

Potential explanations for aggregate variation in lethality rates may be found in the causal mechanisms presented in Baumer, Vélez, and Rosenfeld’s (2018) deductive classification of the assumptions of macro-level criminological theory. One class of mechanisms in their scheme includes the technology available to motivated offenders in criminogenic situations that facilitate lethal actions. Firearms are an obvious candidate for a focal explanatory variable—what Eisner (2008) refers to as the “technology of killing.” When lethal weaponry is abundant, the frequency with which disputes culminate in killings should be higher. Such a pattern was observed in frontier towns in the American West (Courtwright, 1998). The accessibility of firearms depends, to some extent, on numerous legal restrictions. Recent times have witnessed a trend in which several states have passed increasingly permissive firearms laws. Many such laws have expanded the number of public settings in which firearms can be carried while, at the same time, eliminating various restrictions on firearm purchases and concealed carry practices. Recent evidence indicates that the repeal of Missouri’s permit-to-purchase requirement was associated with an increase in gun but not nonhomicides (Webster, Crifasi, & Vernick, 2014). An argument based on the role of opportunity structures and lethal technology suggests changes in the settings where firearms are carried and by whom may account for some of the variation in dispute lethality. Note, however, that these two facets are independent of the effects of the general prevalence of firearms on lethality rates.

Variation in the frequency of lethality may also be explained indirectly by an expansion in opportunity structures that encourage grievances and thus the formation of disputes, particularly the growth in activities beyond the usual reach of legal protections (see Felson & Cundiff, 2018). Put differently, whenever circumstances create opportunities for activities that encourage disputes within contexts of unlawful marketplace exchange, this may correspond with a rise in lethality. Certain contexts in which disputes unfold are especially conducive to lethal outcomes. It is the variation in those contexts that may be important for tracing the sources of lethality trends. An example can be found in circumstances of illicit market exchange. Without access to agents of the state to regulate exchange, protect against predation, and punish rule violators, dealers and sellers of illicit goods and services are apt to employ their own brand of street justice which often rivals the intensity of formal sanctions. Many market actors recognize that they “cannot really be ‘victims’ in the eyes of the criminal justice system” (Topalli, Wright, & Fornango, 2002, p. 337). Although illegal enterprise is generally peaceful, incidents of predation are not unusual. According to Jacobs (2000), drug dealers make “good victims” (pp. 76-77): They carry cash and valuable contraband, and when victimized, they are reluctant to contact legal authorities. The same applies to purchasers. Owing to the assorted costs associated with victimization (e.g., financial loss), seldom can market actors afford to ignore threats posed by rivals. Those who fail to uphold a formidable image possibly invite future exploitation.

Thriving illicit markets provide abundant opportunities for interpersonal disputes, but from my perspective, they add even more to the equation: Illicit markets raise the situational incentives for lethal incapacitation. Within the essentially stateless context of an illicit drug market, killing a rival provides clear assurance that they are no longer a threat. After all, the state is a rather weak third party and can provide only limited protection. The decision to kill an opponent in this particular context could reflect what social psychological models consider an “adversary effect” (see Felson et al., 2014). Examples of such a strategy have been found in corporate bargaining and international relations (see de Mesquita, Morrow, & Zorick, 1997; Pruitt & Rubin, 1986), including corporate raiding during the post-Soviet transition.

As markets for illicit goods and services expand, both the frequency of interpersonal disputes and their lethality may vary accordingly. Perhaps this same type of adversary effect accounted for the high levels of homicide among young African American men in the crack-cocaine era of the 1990s (see Blumstein, 1995). In the same way, the recent growth in the illicit exchange of heroin and synthetic drugs may have contributed to the brief surge in homicide rates (Rosenfeld, 2016). Of course, fluctuations in the illicit economy are closely connected to the overall performance of the licit economy (Rosenfeld, 2009), and these twin dynamics intersect with different population subgroups and institutional controls to produce varying homicide rates.

Another important source of trends in lethal escalation may be found in cultural mechanisms related to honor as well as to the collective authority granted to the state (Baumer et al., 2018). Regarding the former mechanism, scholars have argued that deadly altercations are an expression of conduct norms in which “toleration—if not encouragement—of violence is part of the normative structure” (Wolfgang, 1958, p. 329). Honor-related norms are consequential for the incidence of lethal violence because they encode a strong emphasis on the maintenance of one’s reputation, lower the threshold of insult, condone violent reactions, and redefine violations of self in an adversarial manner (Cooney, 1998). They involve both abstract and strategic goals which serve collective and individual purposes (Gould, 1999). Most of all, codes of honor emphasize interpersonal behaviors which simultaneously facilitate dispute escalation and condemn actions favoring remediation (Horowitz, 1983). Put simply, they enable the escalation process.

Honor-related norms emerge in some settings to fill a perceived absence of formal law. They are also intertwined with concerns about the legitimacy of the state and its authority to both provide protection and allocate resources fairly (Gould, 1999; Tyler, 2006). These and similar cultural mechanisms have been linked to changes in homicide rates both in the United States and internationally (LaFree, 1998; Pinker, 2011). When citizens express strong doubts about state power and become increasingly cynical, there is a greater tendency for individuals to enlist informal methods of social control, often encoded in honor-related norms, to police interpersonal disputes. Roth (2009) argues that sentiments about the law and political institutions and the extent to which they embody the normative currents of the citizenry are critical to understanding the history of lethal violence patterns in the United States, particularly regional differences. Political instability, legislative intransigence, and acute ideological partisanship combine, at times, to erode faith in formal legal institutions and eventually their dispute resolution capacities. Roth (2009) further argues that rising doubts about the legitimacy of informal status hierarchies can produce cynical sentiments that have similar effects on the production of serious and deadly violence.

Other macro-level theoretical explanations also hold potential value for predicting trends in the lethality of conflict (see Eisner, 2008). Some of these focus on shifting individual propensities and other explanations discuss variation in empathy, moral restraint, and changes in collective social controls. The preceding discussion has highlighted the macro-level processes that encourage escalatory tendencies and has largely omitted those that encourage remediation. Cultural and social organizational processes also theoretically govern tendencies to restrain escalatory actions. Furthermore, implicit to many of these macro-level explanations are nuanced arguments about period and cohort variation in the incidence and prevalence of serious violent crime (Berg, Baumer, Rosenfeld, & Loeber, 2016). However, for the sake of brevity, the assumptions found in many other relevant theoretical explanations will not be reviewed here.

Current Study

Prior research on homicide trends in the United States has largely ignored trends in the lethality of disputes. Past work has not adequately attended to the idea that killings result from the escalation of disputes, many of which are frequent but minor in nature, often involving limited aggression and no injury to victims. As noted, a key assumption of this study argues that the volume of interpersonal disputes in a society, and the proportion of those that result in deadly violence, can vary independently. To begin to address these claims, I compute disaggregated trends in the lethality of interpersonal disputes from 1992 through 2016 in the United States.

Data and Method

The current study examines trends from 1992 through 2016, during which time homicide rates peaked and eventually declined, and then remained largely stable until they exhibited an abrupt spike from 2014 to 2016. Data on homicide counts from 1992 to 2016 were obtained from a multiply imputed database of murders and nonnegligent homicides developed by Fox and Fridel (2018) from the SHR. The SHR is not without limitations even though it provides the most comprehensive public account of the nation’s homicide burden. Each year a fraction of law enforcement agencies does not report homicide data to the Federal Bureau of Investigation (FBI), which is responsible for the management of the SHR. In addition, detailed information on the characteristics of victims, offenders, and the homicide incident is missing for a nontrivial proportion of SHR cases, leaving incomplete records for many cases.

Fox and Fridel (2018) developed a two-stage multivariate strategy to impute incomplete information on reported homicides and missing cases of homicide not reported to the SHR (see Fox & Swatt, 2009). From Fox and Fridel’s (2018) database, I computed the homicide victimization counts for individuals aged 12 and older. The counts were then converted to rates using population denominators generated by the U.S. Census Bureau for the NCVS (1992-2016). Next, I disaggregated homicide vicimization rates by gender, census region (South, North, Midwest, West), and a three-category victim race variable: Black, White, and other. The SHR files classify victims who are not Black or White into an “other racial group” variable category, which unfortunately limits the ability to compare lethality in a variety of other racial groups. The SHR does not report counts of homicides by Hispanic ethnicity (see Rosenfeld & Fox, 2019). Due to the measurement limitations associated with racial classification, I do not report the estimates for “other racial groups” in the “Results” section, but they are available upon request.

Using the NCVS raw files, I computed estimates of a composite count of several victimizations reported in NCVS assault incidents. These were classified as serious (non-lethal) disputes. The composite measure is composed of counts of self-reported (a) verbal threats of assault with a weapon, (b) simple assaults with minor injury, (c) assaults without a weapon and without injury, and (d) verbal threats of assault.³ Note that the NCVS measures are not ideal indicators of the volume of serious disputes for several reasons. First, most incidents of minor violence included in the measure probably also involved threats; therefore, these incidents, by implication, had escalated to some degree. Second, the composite measure combines incidents of verbal threats with victimization incidents that involved some form of minor violence. This means the measure includes incidents of varying levels of seriousness, anywhere from verbal threats to physical harm—some incidents escalated more than others. Third, the measure does not include nonviolent threats, such as threats to withhold resources or reveal damaging information. Nonviolent threats both incite grievances and can serve as provocations. Fourth, although not necessarily a measurement limitation, the term dispute indicates bilateral aggression, whereby both (or more) disputants engage in physical aggression. The victimizations captured in the NCVS may well capture incidents involving a “pure victim” or an individual who did nothing, intentionally or not, to provoke the offender. However, the literature shows that many verbal and physical assault victimizations such as those reported in the NCVS involve some form of provocation where the victim and offender exchange verbal and physical provocations, and therefore, they represent interpersonal disputes (e.g., Berg & Felson, 2016). Finally, respondents reported a smaller number of verbal threat victimizations than incidents of physical violence. Perhaps the count of threats is lower than expected because respondents did not deem certain, less severe incidents of threats as worthy of reporting to the NCVS. Still, the NCVS measures used in this study provide the best available tool to explore lethality given that no other nationally representative source of such information exists.

As noted earlier, robbery is a mixed offense where perpetrators are known to pursue purely predatory and purely moralistic motives and sometimes both in the same incident. From the NCVS raw files, I obtained estimates of the reported number of attempted and completed robbery victimization incidents. These are separate from the serious disputes reported by respondents.

To create ratio measures, serious dispute and robbery counts were converted to rates per 1,000 (persons aged 12 and older) based on NCVS annual population counts. When computing the NCVS dispute and robbery estimates, I treated series victimizations as equivalent to a single incident. These count estimates were adjusted by a series weight (see Lauritsen, Heimer, & Lynch, 2009). Rates were computed for gender, U.S. census region, and a three-category variable of race (Black, White), the latter of which aligns entirely with the race variable available in the imputed SHR file.⁴ I substituted estimates of simple assault, available in the Bureau of Justice Statistics annual printed reports, for the measure of serious disputes to compute regional comparisons from 1993 to 1995 because these yearly estimates were not available in the NCVS file.

The analysis is mainly descriptive largely because the limited number of years does not permit time-series or multivariate analysis and partly because the study simply intends to illustrate, at a basic level, how to conceive of lethal escalation in a macro-level context. The lethality of disputes and robberies is assessed using rate ratios. The counts of homicide, serious disputes, and robberies were divided by the annual population (aged 12 and older) and multiplied by 1,000. Next, the homicide rate was divided by the robbery rate to produce a rate ratio or robbery lethality ratio, which reports the average number of killings for every robbery. That ratio was then multiplied by 1,000 to reflect the number of killings for every 1,000 reported robbery incidents. The same series of calculations was applied to serious disputes and homicide victimization rates to generate the dispute lethality ratio (i.e., the number of killings for every 1,000 reported serious disputes). The ratios measure the degree to which disputes and robberies escalate to deadly violence. Put differently, they reflect how frequently victimizations result in killings, on average, each year.

I begin with a graphical depiction of national trends in serious disputes, robbery, and homicide. I then report bivariate detrended correlations. Next, I present trends in the lethality ratios disaggregated by region of the United States, gender of the victim, and race. This is followed by a presentation of lethality ratios differentiated by gun and nongun homicide.

Results

Figure 1 illustrates trends in the rates of homicide, robbery, and serious dispute victimization from 1992 through 2016 for persons aged 12 and older in the United States. Note that the trends are expressed in different per capita rates for comparison purposes. A handful of patterns are worth noting: Most notably, the rates have been on a gradual decline since 1992. Turning to the recent period of interest, rates of homicide increased 9.1% from 2014 to 2016 (Rosenfeld & Fox, 2019), serious disputes rose by about 14%, whereas the robbery rate declined by 18.6%.

Figure 1.

Serious dispute, robbery, and homicide rates (aged 12 and older): U.S. total (1992-2016).

It appears that national trends in robbery, serious disputes, and deadly violence follow similar patterns, but are they interchangeable measures of interpersonal conflict in society? Table 1 provides bivariate detrended correlations to try to answer these questions. Each series was converted to first differences to remove their common time trend (see Enders, 2008). Homicides are more strongly correlated with disputes than with robbery (.536 vs. .357), although the former correlation is only moderately strong. This pattern suggests serious disputes and homicide are independent indicators of the frequency of violence in the United States although they are moderately associated with one another. Furthermore, the first-differenced correlations indicate that dispute and robbery rates are significantly and moderately correlated (.576), giving credibility to the assumption that an appreciable fraction of robberies entail moralistic disputes. Note, however, that detrended correlations can be unreliable in short time series such as the current one.

Table 1.

First-Differenced (Detrended) Correlations Between Series Rates (N = 24).

	(A)	(B)	(C)
(A) Homicide rate	1
(B) Robbery rate	.357**	1
(C) Serious dispute rate	.536**	.576**	1

Note. Rate correlations computed per 1,000.

p < .05.

Turning now to the lethality ratios, Figure 2 reports the ratios for disputes and robbery for persons aged 12 and older in the United States. Figure 2a shows that the serious dispute ratio rose from 2012 to 2015 when it peaked, such that there were approximately 5.7 murders for every 1,000 disputes. At its lowest level in 1998, the lethality ratio was 2.6, indicating that, on average, there were 2.6 killings for every 1,000 serious disputes. The increasing ratio indicates there has been a gradual increase the number of murders for every assault, with some exceptions, suggesting that disputes have become increasingly deadly over time. Perhaps people were more likely to “get by” with engaging in serious conflict in the recent past compared to the presnt day.

Figure 2.

Lethality ratios (aged 12 and older): U.S. total (1992-2016): (a) serious dispute lethality ratio (number of homicides per 1,000 serious disputes); (b) robbery lethality ratio (number of homicides per 1,000 robberies).

The robbery lethality ratios reported in Figure 2b show a gradual increase since 1992 marked by periodic, albeit brief, upward and downward swings. Robbery victimizations have become less frequent since 1992 (see Figure 1), but the risk of murder for every robbery victimization incident has gradually grown. The fact that robbery victimizations have become less frequent should be taken into account when assessing these trends. The period from 2014 to 2016 saw a 47% increase in the lethality ratio, meaning there were more murders for every robbery, and therefore, robbery altercations were deadlier over this period.

It is useful to partition the total change in rate ratios between 1992 and 2016 by gender, race, and region. Not surprisingly, the estimates reveal that levels of lethality vary by gender. As shown in Figure 3a, the male lethality ratio for serious disputes is considerably higher than the female ratio, on average by multiples of 3.3. For instance, in 2016, women experienced 5.5 fewer murders per 1,000 serious disputes than men. A similar story emerges in Figure 3b where the robbery victimization trends by gender are under the microscope. The female lethality ratio is lower throughout the series by an average factor of 2.3, suggesting robbery victimizations less often result in killings for women versus men. Women experienced 31.4 killings for every 1,000 robberies in 2014, whereas men suffered 12.2 killings.

Figure 3.

Lethality ratios (aged 12 and older) by gender (1992-2016): (a) serious dispute lethality ratio (number of homicides per 1,000 serious disputes); (b) robbery lethality ratio (number of homicides per 1,000 robberies).

As is evident in Figure 3, from 2014 to 2016 the serious dispute lethality ratio among women increased just slightly by about 8.7%, whereas for male victims it spiked (after growing since around 2012) and then declined. The robbery lethality ratio in Figure 3b increased by more than 25% among women, and among men by more than 61%. Robbery incidents were more likely to result in violent deaths from 2014 to 2016 than in the immediately preceding years. Men, however, endured the brunt of the lethality increase during that particular period.

Do trends in lethality vary by race? Figure 4 suggests they do, and by a wide degree. Note, however, here I provide only a brief description of Black–White patterns and do not show rates for the “other” category due to measurement uncertainty. As shown in Figure 4a, the gap in the dispute lethality ratios for Blacks and Whites is substantial. The Black rate ratio was roughly 7.2 times higher than the White rate ratio throughout the 1990s, and although the gap declined slightly in the 2000s, the Black lethality ratio remained roughly 6.2 times higher. For instance, in 2014, Black victims experienced 17.7 killings for every 1,000 disputes compared with 2.8 killings among Whites. More striking is the fact that Black and White victims reported comparable rates of serious dispute victimizations, with Whites experiencing more than Blacks in some years (estimates not shown in tabular form). Specifically, the average rate of serious disputes among Blacks was 21.6, and among Whites it was 20.7. Comibined, the evidence indicates that serious disputes appear to be deadlier for Blacks than Whites. From 2014 to 2016, the Black victim lethality ratio grew by 21.3%, trending toward greater lethality. For Whites, it barely moved.

Figure 4.

Lethality ratios (aged 12 and older) by race (1992-2016): (a) serious dispute lethality ratio (number of homicides per 1,000 serious disputes); (b) robbery lethality ratio (number of homicides per 1,000 robberies).

The estimates in Figure 4b report that the robbery lethality ratios were consistently lower among White than Black victims. Robbery more frequently results in murder for the latter group than the former. The gap between the groups narrowed owing to larger increases in the White ratio. From 2014 to 2016, when homicide rates rose nationally, both racial groups experienced a sharp increase in robbery lethality, indicating a trend toward deadlier altercations. However, the increase in robbery lethality from 2014 to 2016 was larger for Whites (63.1%) than for Blacks (40.0%). Any explanation of trends in lethality will have to account for racial differences.

Regional differences in serious dispute lethality are displayed in Figure 5a. The trends have generally increased across regions but have occasionally diverged from this pattern, particularly around 2010 through 2014 when the ratios declined. It is obvious from the graphs that serious disputes in the South have a substantially higher lethality ratio than in other regions of the country. Additional analyses not shown indicated that Southern rates of dispute victimizations (average 16.7) were, on average, lower or very near the rates in the Midwest (20.7), West (23.5), and Northeast (16.5). What this suggests is that the South is not necessarily more violent than other regions of the country; rather, it is an especially dangerous place to have an altercation.

Figure 5.

Lethality ratios (aged 12 and older) by region (1992-2016): (a) serious dispute lethality ratio (number of homicides per 1,000 serious disputes); (b) robbery lethality ratio (number of homicides per 1,000 robberies).

According to the regional estimates, the rate of dispute lethality rose in the Midwest from 2014 to 2016 (38.5% rise), whereas the Western region saw an opposite pattern over the same period—a trend of fewer homicides for every 1,000 disputes, and thus less lethal conflict. The Southern and Northeastern lethality ratios increased just slightly from 2014 to 2016.

As reported in Figure 5b, in the West, Midwest, and Northeast, robberies have become deadlier in some years and less deadly in others with wide oscillations. Again, the South is the outlier because there robbery more often results in murder. Particularly noteworthy is the general increase in the lethality ratio from 2014 to 2016 across the four regions. For instance, the lethality of robbery incidents increased by almost 90% in the Midwest, 42% in the South, 34% in the Northeast, and just 28% in the West, where the ratio has gradually grown since 2012. A similar pattern is evident from around 1999 through 2002.

Finally, it is instructive to compare national trends in the lethality of disputes for gun and nongun homicides to learn more about the role of firearms. So far, the analyses have accounted for the total homicide rate, ignoring differences by lethal weaponry, particularly whether the act was committed with a firearm.

Figure 6a displays trends in serious dispute lethality ratios for gun and nongun homicides. Disaggregated homicide counts were obtained from the imputed SHR file (Fox & Fridel, 2018). From 1992 through 2016, the nongun lethality ratio increased by 38.6% and the gun lethality ratio by 83.6%. Serious dispute victimizations became deadlier over time, in large part, due to mounting risk of gun homicides. Perhaps this trend resulted from an expansion of the situations in which guns were used by disputants. The nongun lethality ratio declined from 2014 to 2016 such that dispute incidents become less deadly, whereas the gun ratio rose by 11.5%. This latter trend in the gun ratio is suggestive of a small increase in serious dispute lethality.

Figure 6.

Lethality ratios (aged 12 and older) by gun and nongun homicide (1992-2016): (a) serious dispute lethality ratio (number of homicides per 1,000 serious disputes); (b) robbery lethality ratio (number of homicides per 1,000 robberies).

Figure 6b illustrates the disaggregated trends in robbery across gun and nongun homicide aggregate rates. The estimates reveal that the lethality of the nongun homicide per robbery ratio rose by 62.4% since 1992, which is significantly less than the 116% increase in gun homicides per 1,000 robbery victimizations. Across the series, the gun homicide per robbery ratio was substantially higher than the nongun homicide per robbery ratio, which is indicative of the greater lethality risk of gun robberies. These findings are consistent with prior evidence: When a robbery victim is injured, even though minor injury is less likely when guns are involved (see Cook, 1987), they are much more likely to die if the weapon is a gun. The graphs also illustrate simultaneous increases in the robbery lethality ratios across the gun and nongun categories from 2014 to 2016. Robbery lethality increased by 57.1% for gun killings and by 23.3% for nongun killings. During this brief period more murders per 1,000 robbery victimizations occured than in prior years. Robberies therefore were increasingly likely to result in killings due, in no small part, to the growth in lethal incidents involving firearms.

Combined, a larger proportion of robbery and serious dispute victimization incidents become gun homicides compared with nongun homicides. Firearms play an important role in contemporary homicide rates because they boost the lethality of predatory and moralistic altercations.

Discussion and Conclusion

The purpose of this study was to illustrate the value of a lethality framework for conceiving of the proximate dispute-related processes underlying aggregate homicide rates. The social conditions that govern the frequency with which interpersonal disputes erupt into killings have not been adequately studied. This article addressed important questions necessary for resolving some of the puzzles of contemporary homicide trends: Does the lethality of disputes vary across time? And, more narrowly, did rates of lethality change from 2014 to 2016 in ways to account for the abrupt spike in homicide over that brief period?

First, the estimates showed that, generally spoeaking, there has been a gradual increase in the number of homicides for every serious dispute and robbery victimization incident. Meanwhile, for the most part, the total rate of homicide has continued on a downward trajectory. Although the frequency of robbery and serious disputes has gradually declined since 1992, the frequency with which they result in deadly altercations has grown. Put differently, the United Sates has become more peaceful, but its disputes have become deadlier. We can look to other advanced capitalist nations to find roughly parallel cases. Countries with relatively high levels of interpersonal violence are not necessarily the same countries with high murder rates (Felson et al., 2014; Zimring & Hawkins, 1999). The United Kingdom is a representative example.

The aggregate trends also indicated that robbery is a far more fatal interaction than serious disputes, with a lethality ratio that was substantially higher than the dispute ratio across the series. Arguably, this pattern partly reflects the fact that robbery is rarer than serious disputes, and therefore, robbery yields a higher lethality ratio. Nonetheless, whether many of the robberies reported in the NCVS are dispute-related, purely predatory, or a combination of moralistic and predatory motives is impossible to know with certainty. To the extent they are partly motivated by moralistic concerns, it is reasonable to say that deadly robberies unfold by way of the escalatory processes common to lethal disputes (see Wright & Decker, 1997). Whatever the underlying motives of the actors involved, robberies became deadlier from 2014 to 2016 as demonstrated by a rather marked increase in the lethality ratio within that period. The increase exceeded that of serious disputes. Any attempt to explain the rise in homicide from 2014 to 2016 must consider why disputes and robberies, but especially robbery incidents, were suddenly more likely to result in murder. It is important to stress to readers, however, that the abrupt rise spanning 2014-2016 was not all too distinct from prior upswings and downswings in the lethality ratios.

Second, aggregate national trends obscured important variation found in several population subgroups. For example, comparisons by gender found that women’s lethality risk was substantially lower than the risk among males. Women reported fewer homicides per dispute and robbery than men. A set of estimates not shown in tabular form also indicated that the gender gaps in the frequency of dispute and robbery victimizations have narrowed since 1992 (see Lauritsen et al., 2009). The fact that men and women suffered comparable levels of serious dispute and robbery victimizations but men’s lethality rates remained much higher indicates a gender disparity not in violence per se, but in dispute lethality. Social psychological models would suggest that this gender disparity, to some extent, reflects an adversary effect: During an altercation, individuals are especially inclined to kill a male antagonist (vs. a women) owing to perceptions of their superior coercive power. Part of the answer to questions about the rise in homicide from 2014 to 2016 might be found if one accounts for the sizable increase in robbery lethality for men and women alike.

The comparisons between Black and White victims made obvious the racial disparity in lethality trends that is obscured in trends in the total homicide rate. Estimates not shown in tabular form also indicated there were minimal differences between Blacks and Whites in rates of serious dispute victimization. On average, however, conflicts more often ended in lethal outcomes for Black victims. What the findings clearly suggest is that Black victims were more likely than Whites to experience deadly robbery and dispute incidents. Researchers have argued that such racial disparities in the nature of violent victimization might also emerge from a type of adversary effect (Berg, 2014). From the perspective of criminological theories of community processes, racial disparities in lethality may be a product of group differences in exposure to disadvantaged social environments in which honor cultures flourish—cultures that endorse retaliatory exchange (see Cooney, 1998; Sampson & Wilson, 1995).

Around 2014, the lethality risk of serious disputes grew for Blacks by a larger fraction than for White victims. Robbery trends revealed a different pattern in that they became somewhat deadlier for Whites than Blacks from 2014 to 2016. The fact that both groups experienced a surge in lethality suggests the brief homicide spike partly resulted from group-invariant mechanisms. Perhaps the expansion of illicit markets for heroin and synthetic drugs holds important clues about the sources of the spike. Other scholars have reported that drug homicides increased by 33% among the general population (Rosenfeld & Fox, 2019). There is a debate about the degree of racial similarities in opioid and synthetic drug use (see Harrison, Lagisetty, Sites, Guo, & Davis, 2018); however, according to public health statistics, since 2011 these classes of drugs have adversely affected both populations as indicated by their rising overdose mortality rates (Alexander, Kiang, & Barbieri, 2018). The possibility that the expansion of heroin and synthetic drugs markets was a key source of the recent abrupt surge in homicide requires additional investigation. If the crack-cocaine era is any guide, the emerging markets for these drugs may have generated opportunities for violent acts of predation infused with moralistic motives (Bernasco & Block, 2011; Jacobs, 2000). Researchers should consider how illicit drug markets, in a time of declining state legitimacy and a gradual erosion of institutional trust (Citrin & Stoker, 2018), may have increased incentives for lethal incapacitation.

Turning to regional comparisons, robbery and serious disputes were deadlier in the American South. In fact, the Midwest, West, and Northeast trends in dispute lethality were roughly equivalent and their contours generally followed one another across the series. Additional estimates from the NCVS not reported in the “Results” section revealed that Southern rates of serious disputes were, on average, lower or just slightly above rates in the other regions (e.g., South, M = 16.7 vs. West, 23.5). This pattern suggests that lower level disputes are not more common in the South compared to other places; yet, in the South, conflicts are more likely to result in murder. Perhaps a regional honor code can explain the lethality of Southern conflict (Roth, 2009). The code may suppress or deter minor forms of conflict while, at the same time, raise the situtational incentives for killing an adversary. The lethality of robbery in the South is higher as well in comparison to other regions.

Finally, the estimates of lethality across gun and nongun homicides are instructive for purposes of developing explanations for lethality trends and, more generally, for aggregate homicide rates. These results are suggestive of the possibility that serious dispute and robbery victimization incidents have a greater tendency to culminate as homicides when firearms are involved. Put differently, a larger fraction of robbery and dispute incidents result in gun versus nongun killings (see Cook, 1987). On balance, the findings favor the perspective that the availability of firearms increases the lethality of comparatively minor forms of conflict and predation. What can this evidence tell us about the recent abrupt spike in homicide rates from 2014 to 2016? Let’s revisit the facts: The lethality of robbery and serious dispute victimizations increased in the case of gun homicides from 2014 to 2016. For nongun homicides, lethality rose as well, but by a smaller fraction and only among robbery victimization incidents. As noted earlier, at the same time, gun homicides in the total population increased by more than 30% (Rosenfeld & Fox, 2019). Together, these facts provide good reasons to surmise that either a growing presence of firearms or a surge in offenders motivated to use firearms to kill an adversary, or perhaps both circumstances, had a critical role in the homicide surge from 2014 to 2016.

Scholars of violent crime trends should not fixate on temporal variation in the stock and flow of the private gun arsenal to predict aggregate homicide rates. Nor should they assume that the volume of guns, in general, will immediately correlate with higher homicide rates. Rather, researchers may want to dedicate more attention to trends in the accessibility of firearms, especially to certain people with elevated propensities for their unlawful use, and to temporal differences in the social contexts in which firearms are lawfully and unlawfully carried (e.g., Webster et al., 2014). Researchers should also not lose sight of the way changes in facets of lethal technology (e.g., where guns are carried) might overlap with the expansion of illicit opportunities and the erosion of state legitimacy, whether at the federal or local levels.

The study is not without limitations. The victimization items from the NCVS represent only crude approximations of serious interpersonal disputes. They are proxy variables. Measures with better construct validity would include less serious but even more frequent disputes of the type that probably would not be reported to the NCVS. In addition, the small number of years in the time series does not allow for conclusions about how the patterns from 1992 through 2016 fit into long-term trends dating back several decades. For this reason, the findings represent only a snapshot of American violence trends. The study is also limited by its inability to test the interactional processes described in the discussion of social psychological models (e.g., coercive power; see Berg & Felson, 2016; Tedeschi & Felson, 1994). Nonetheless, the evidence from this assessment squares with the conception of disputes and lethal escalation presented in the current approach. Further, the study was not able to report rates by Hispanic ethnicity. Finally, the ability of the current study to partition lethality trends by racial groups was limited to Black-White differences owing to the crude categorization of certain racial groups as “other” – a classification which masked the racial identities of several population subgroups.

In conclusion, the present study attempted to demonstrate the potential value of a social psychological framework of aggression to interpret aggregate violence trends. It is reasonable to argue that the spike in homicide from 2014 to 2016 resulted from increases in dispute and robbery lethality, but only among certain population subgroups. The findings point to the potential explanatory roles of opportunity structures, cultural mechanisms, and changes in the technology of killing. Consulting what is traditionally a micro-level explanation of aggression might stimulate new hypotheses from macro-level criminological theories about trends in lethality, independent of the frequency of interpersonal disputes.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Fellowship support for this research was provided to the author by the Obermann Center for Advanced Studies (University of Iowa).

Notes

ORCID iD

Mark T. Berg

Author Biography

Mark T. Berg is an associate professor in the Department of Sociology at the University of Iowa. His current research examines the situational context of interpersonal violence and the social determinants of health and well-being.

References

Alexander

M. J.

Kiang

M. V.

Barbieri

(2018). Trends in black and white opioid mortality in the United States, 1979-2015. Epidemiology, 29, 707-715.

Baumer

E. P.

Vélez

M. B.

Rosenfeld

(2018). Bringing crime trends back into criminology: A critical assessment of the literature and a blueprint for future inquiry. Annual Review of Criminology, 1, 39-61.

Benard

Berg

M. T.

Mize

T. D.

(2017). Does aggression deter or invite reciprocal behavior? Considering coercive capacity. Social Psychology Quarterly, 80, 310-329.

Berg

M. T.

(2014). Accounting for racial disparities in the nature of violent victimization. Journal of Quantitative Criminology, 30, 629-650.

Berg

M. T.

Baumer

Rosenfeld

Loeber

(2016). Dissecting the prevalence and incidence of offending during the crime drop of the 1990s. Journal of Quantitative Criminology, 32, 377-396.

Berg

M. T.

Felson

R. B.

(2016). Why are offenders victimized so often? In Cuevas

C. A.

Rennison

C. M.

(Eds.), The Wiley handbook on the psychology of violence (pp. 49-65). West Sussex, UK: John Wiley.

Bernasco

Block

(2011). Robberies in Chicago: A block-level analysis of the influence of crime generators, crime attractors, and offender anchor points. Journal of Research in Crime and Delinquency, 48, 33-57.

Black

(1983). Crime as social control. American Sociological Review, 48, 34-45.

Blumstein

(1995). Youth violence, guns, and the illicit-drug industry. Journal of Criminal Law and Criminology, 86, 10-36.

10.

Citrin

Stoker

(2018). Political trust in a cynical age. Annual Review of Political Science, 21, 49-70.

11.

Cody

M. L.

McLaughlin

M. J.

(1988). Accounts on trial: Oral arguments in traffic court. In Antaki

(Ed.), Analysing everyday explanation: A casebook of methods (pp. 113-126). Thousand Oaks, CA: Sage.

12.

Cook

P. J.

(1987). Robbery violence. Journal of Criminal Law and Criminology, 78, 357-376.

13.

Cook

P. J.

(2013). The great American gun war: Notes from four decades in the trenches. Crime and Justice, 42, 19-73.

14.

Cook

P. J.

Ludwig

(2004). Does gun prevalence affect teen gun carrying after all? Criminology, 42, 27-54.

15.

Cooney

(1998). Warriors and peacemakers: How third parties shape violence. New York: New York University Press.

16.

Courtwright

D. T

. (1998). Violent land: Single men and social disorder from the frontier to the inner city. Cambridge, MA: Harvard University Press.

17.

de Mesquita

B. B.

Morrow

J. D.

Zorick

E. R

. (1997). Capabilities, perception, and escalation. American Political Science Review, 91, 15-27.

18.

Deutsch

Krauss

R. M.

(1962). Studies of interpersonal bargaining. Journal of Conflict Resolution, 6, 52-76.

19.

Eisner

(2008). Modernity strikes back? A historical perspective on the latest increase in interpersonal violence (1960-1990). International Journal of Conflict and Violence, 2, 288-316.

20.

Enders

(2008). Applied econometric time series. Hoboken, NJ: John Wiley.

21.

Felson

R. B.

Berg

M. T.

Rogers

M. L.

(2014). Bring a gun to a gunfight: Armed adversaries and violence across nations. Social Science Research, 47, 79-90.

22.

Felson

R. B.

Cundiff

P. R.

(2018). The gold rush and afterwards: Homicide in San Francisco, 1849-2003. Aggressive Behavior, 44, 601-613.

23.

Fox

J. A.

Fridel

E. E.

(2018). Codebook for the multiply-imputed supplementary homicide reports file 1976-2016. Boston, MA: School of Criminology and Criminal Justice, Northeastern University.

24.

Fox

J. A.

Swatt

M. L.

(2009). Multiple imputation of the supplementary homicide reports, 1976-2005. Journal of Quantitative Criminology, 25, 51-77.

25.

Gould

R. V

. (1999). Collective violence and group solidarity: Evidence from a feuding society. American Sociological Review, 356-380.

26.

Harrison

J. M.

Lagisetty

Sites

B. D.

Guo

Davis

M. A.

(2018). Trends in prescription pain medication use by race/ethnicity among US adults with noncancer pain, 2000-2015. American Journal of Public Health, 108, 788-790.

27.

Horowitz

(1983). Honor and the American dream: Culture and identity in a Chicano community. New Brunswick, NJ: Rutgers University Press.

28.

Jacobs

(2000). Robbing drug dealers: Violence beyond the law. New York, NY: Aldine de Gruyter.

29.

LaFree

(1998). Losing legitimacy: Street crime and the decline of social institutions in the United States. Boulder, CO: Westview Press.

30.

Lauritsen

J. L.

Heimer

Lynch

J. P.

(2009). Trends in the gender gap in violent offending: New evidence from the National Crime Victimization Survey. Criminology, 47, 361-399.

31.

Luckenbill

D. F.

(1977). Criminal homicide as a situated transaction. Social Problems, 25, 176-186.

32.

Phillips

Maume

M. O.

(2007). Have gun will shoot? Weapon instrumentality, intent, and the violent escalation of conflict. Homicide Studies, 11, 272-294.

33.

Pinker

(2011). The better angels of our nature: The decline of violence in history and its causes. London, England: Penguin Books.

34.

Pruitt

D. P.

Rubin

(1986). Social conflict: Escalation, stalemate, and settlement. New York, NY: McGraw-Hill.

35.

Rosenfeld

(2009). Crime is the problem: Homicide, acquisitive crime, and economic conditions. Journal of Quantitative Criminology, 25, 287-306.

36.

Rosenfeld

(2016). Documenting and explaining the 2015 homicide rise: Research directions. Washington, DC: National Institute of Justice, U.S. Department of Justice.

37.

Rosenfeld

Fox

J. A.

(2019). Anatomy of the homicide rise. Homicide Studies, 23, 202-224. doi: 10.1177/1088767919848821

38.

Rosenfeld

Messner

S. F.

(2013). Crime and the economy. Thousand Oaks, CA: Sage.

39.

Roth

(2009). American homicide. Cambridge, MA: Belknap Press.

40.

Sampson

R. J.

Wilson

W. J.

(1995). Toward a theory of race, crime, and urban inequality. In Hagan

Peterson

R. D.

(Eds.), Race, crime, and justice: A reader (pp. 37-56). Stanford, CA: Stanford University Press.

41.

Schelling

T. C.

(1980). The strategy of conflict. Cambridge, MA: Harvard University Press.

42.

Tedeschi

J. T.

Felson

R. B.

(1994). Violence, aggression, and coercive actions. Washington, DC: American Psychological Association.

43.

Tedeschi

J. T.

Nesler

(1993). Grievances: Development and reactions. In Felson

R. B.

Tedeschi

J. T.

(Eds.), Aggression and violence: Social interactionist perspectives (pp. 13-45). Washington, DC: American Psychological Association Press.

44.

Tedeschi

J. T.

Smith

R. B.

Brown

R. C.

(1974). A reinterpretation of research on aggression. Psychological Bulletin, 81, 540-562.

45.

Topalli

Wright

Fornango

(2002). Drug dealers, robbery and retaliation: Vulnerability, deterrence and the contagion of violence. The British Journal of Criminology, 42, 337-351.

46.

Tyler

T. R.

(2006). Why people obey the law. Princeton, NJ: Princeton University Press.

47.

Webster

Crifasi

C. K.

Vernick

J. S.

(2014). Effects of the repeal of Missouri’s handgun purchaser licensing law on homicides. Journal of Urban Health, 91, 293-302.

48.

Wells

Horney

(2002). Weapon effects and individual intent to do harm: Influences on the escalation of violence. Criminology, 40, 265-296.

49.

Wolfgang

M. E.

(1958). Patterns in criminal homicide. Philadelphia: University of Pennsylvania Press.

50.

Wright

Decker

S. H.

(1997). Armed robbers in action: Stickups and street culture. Boston, MA: Northeastern University Press.

51.

Zimring

F. E.

Hawkins

(1999). Crime is not the problem: Lethal violence in America. Oxford, UK: Oxford University Press.