In 1970, just months before his death, the historian Richard Hofstadter called on U.S. historians to engage the subject of violence. For a generation, he wrote, the profession had ignored the issue, assuming that consensus rather than conflict had shaped the American past. By the late 1960s, with assassinations, riots, and violent crime at the forefront of national anxieties, that assumption was no longer tenable. Everywhere, Americans seemed to be thinking and talking about violence, except within the historical profession. Hofstadter urged historians to remedy their “inattention” and construct a history of violence that would speak to both the present and the past.[1]

Over the last four decades, the historical profession has responded to that challenge. Studies of racial conflict, territorial massacres, gendered violence, empire, crime and punishment, and war and memory make up some of the most esteemed books of the past generation. Yet on the subject of “terrorism,” the form of violence that currently dominates American political discourse, historians have had comparatively little to say. Since the attacks of September 11, 2001, a handful of conferences have addressed historical aspects of terrorism, from its nineteenth-century origins to its impact on state building and national identity. Scholarly journals (including the Journal of American History) have devoted the occasional special issue to examining terrorism’s roots and present-day implications. Within the historical profession, several book-length works have taken up episodes of terrorism, examining the production of both violence and state repression. Social scientists and journalists have offered sweeping global histories, tracing the problem of terrorism from antiquity to the present.[2]

As a result, we have a better understanding of terrorism’s history than we did a decade ago, but it would be hard to classify this surge of work as a flourishing subfield or even a coherent historiography. Almost a decade out from 9/11, most U.S. historians remain hard-pressed to explain what terrorism is, how and when it began, or what its impact has been. There is little consensus about how best to approach the subject or even whether to address it at all. This is partly because the issue poses knotty political questions: How do we talk about terrorism without reinforcing the “war on terror” or lapsing into hopeless presentism? It also brings serious methodological problems: Is terrorism a word to be traced through centuries of semantic permutation? Is it an epithet to be applied to forms of violence we do not like? Is it a concept to be defined, however loosely, and followed through time?

Like any project that takes its cue from current affairs, constructing a historiography of terrorism requires caution and a light touch. But it also offers an opportunity to ask new questions about the nature of American violence and national identity and to lend perspective to an often-limited, polemical, and ahistorical contemporary debate. This essay provides an overview of the burgeoning historiography of terrorism and suggests how we might integrate such work into narratives of the American past and present.

Many essays on terrorism begin with the deflating admission that nobody knows what terrorism is. This is not, thankfully, entirely true. While social scientists and policy experts enjoy debating the details, most modern definitions share certain elements that distinguish terrorism from other forms of violence. In contrast to ordinary crime, terrorism is widely understood to be a political act, a gesture—however immoral or misguided—toward promoting some greater cause. Unlike the violence of the battlefield, terrorism is primarily a spectacular method of communication aimed at audiences far from the target itself—what the anarchist movement used to describe (rather poetically) as “propaganda by deed.” Within these spheres of agreement, gray areas abound: What distinguishes terrorism from guerrilla warfare? Can formal states be “terrorists”? Much of the debate over definitions, however, merely demonstrates what historians already know: the meaning of terrorism, like any other word or concept, has changed according to its moment in time and its political context.

The scholarly study of terrorism has evolved in tandem with political concerns. A century ago, social scientists viewed terrorism as an offshoot of anticapitalist revolt; anarchists and labor radicals were the “terrorists” of their day. Six decades later, after a lull in interest, experts began to busy themselves with a different sort of revolutionary actor, the anticolonial guerrilla fighters and New Left militants stirring up trouble for the world’s regimes. In both cases, academic directions coincided with policy interests; scholars turned to the study of terrorism when their governments did. In that sense, there is nothing unique about contemporary efforts to reexamine conceptions of terrorism or to ask how and why this particular form of violence began.

Most histories of terrorism start with the French Revolution, when the terms “terror,” “terrorism,” and “terrorist” entered the modern lexicon. The words, then, evoked a form of violence all but forgotten in present-day policy debates. Two centuries ago, the Terror came from those in power; its finest expression was the guillotine, not the bomb. In its earliest manifestations, according to the Oxford English Dictionary, “terrorism” meant “government by intimidation,” “a policy intended to strike with terror those against whom it is adopted.” What happened to the term over the next century remains a developing area of scholarship. We have few studies of the nineteenth-century discourse on terrorism or of how the word was applied in the United States. Scholars have noted that Americans in the mid-nineteenth century used “terrorism” to describe a variety of activities, from strikes and boycotts to the institution of slavery and the terror of the Civil War. It was not until the late nineteenth century, however, that the words “terrorism” and “terrorist” were applied to a discrete form of violence, something to be inspected, claimed, and studied in its own right. After he attempted to assassinate the industrialist Henry Clay Frick in 1892, the anarchist Alexander Berkman boldly—and plausibly—claimed that he had committed “the first terrorist act in America.”[3]

Viewed from a twenty-first-century perspective, Berkman’s statement seems questionable. It does not account for many episodes of violence that have since been classified as possible examples of terrorism, from the brutalities (on all sides) of colonial-era Indian conflicts to the lynchings and other murders perpetrated by the Reconstruction-era Ku Klux Klan. Nor does Berkman’s act resemble the form of violence currently dominating the news: organized, anonymous, international attacks aimed at large groups of civilians. Berkman, however, had a particular tradition in mind when he adopted the “terrorist” label. To him (and to the first generation of social scientists to study the phenomenon), terrorism was a well-theorized revolutionary tactic consisting of targeted, individual attacks against symbols of government and capital. The terms “terrorism” and “terrorist,” in that view, were descriptive rather than pejorative, part of a revolutionary ethos birthed in the Russian revolt against the tsar and subsequently dispersed around the globe. Berkman’s declaration, however self-aggrandizing, revealed an assumption that had become widespread by the early twentieth century: the labels of “terrorist” and “terrorism” belonged to those who launched revolutionary conflict from below.

This understanding dominated the first attempts by American social scientists and historians to assess terrorism as a historical phenomenon. While the Progressive Era yielded no self-described histories of terrorism, both the word and the issue of revolutionary violence permeated the period’s labor and radical scholarship. In his 1914 book Violence and the Labor Movement, the Socialist muckraker Robert Hunter traced what he saw as a lamentable history of violence leading from the Russian anarchist Mikhail Bakunin (“The Father of Terrorism”) through the labor leader Bill Haywood and the Industrial Workers of the World. Twenty years later, the social critic Louis Adamic offered a similar trajectory in his swashbuckling Dynamite: The Story of Class Violence in America. Adamic credited the German anarchist Johann Most with importing the terrorist tradition to the United States. He also lamented that the revolutionary violence of Most’s era had evolved by the 1930s into an apolitical form of “criminal terrorism” characterized by racketeering and intimidation within the country’s labor unions.[4]

Like most early scholars of the subject, Adamic did not spend much time defining his terms; he was interested in class politics, not “terrorism” per se. The one major attempt in that era to pin down the term’s meaning came in 1934, with the publication of The Encyclopedia of the Social Sciences. In its pages, the American editor and labor activist J. B. S. Hardman described terrorism as “the method . . . whereby an organized group or party seeks to achieve its avowed aims chiefly through the systematic use of violence.” Hardman emphasized the symbolic and communicative nature of terrorism, distinguishing it from “mob violence.” He also set it apart from “governmental terror,” suggesting that law enforcement repression, however terrorizing, deserved an analytical category of its own. Terrorism, Hardman concluded, was a clandestine revolutionary tactic designed to destabilize the existing order through well-planned acts of spectacular violence. As exemplars, he cited the anarchist movement, the Fenians of Ireland, and the Russian revolutionaries of the 1870s and 1880s.[5]

Hardman’s approach had much to recommend it. Rejecting a catchall use of the term, he attempted to situate “terrorism” within a consistent historical trajectory. He also noted the two features that would ultimately dominate social science thinking on the subject: terrorism’s political nature and its communicative effects. By the time he proffered his definition, however, interest in the subject was already fading. With World War II on the horizon, others “-isms”—fascism, communism, militarism—presented far more pressing concerns. For U.S. historians, the midcentury turn toward consensus thinking further eroded what little significance the concept of terrorism once held. Hoping to slow the rush toward McCarthyism, consensus historians tended to downplay earlier alarm over revolutionary violence as so much fantasy and “hysteria,” fuel merely for red scares and government backlash.[6]

It was not until the 1970s that terrorism reemerged as a significant area of social science inquiry. The impetus, once again, came from current events. In the United States, the late 1960s and early 1970s brought rising concern about political violence; the debate over what caused and constituted terrorism unfolded alongside discussions of “race riots” and “guerrilla war.” Beyond U.S. borders, the issue of terrorism had already gained prominence, as liberation movements in Palestine, Algeria, Northern Ireland, South Africa, and elsewhere pioneered guerrilla tactics increasingly classified as terrorist attacks. In 1972, responding to this surge in violence, President Richard M. Nixon launched the United States’ first feeble effort to develop a self-proclaimed national counterterrorism policy.[7] Eager to participate in the conversation, a new generation of social scientists set out to apply the tools of sociology, psychology, anthropology, and political science to the meet the growing interest. Out of this effort was born the lively but troubled field of terrorism studies.

Many of the field’s pioneers straddled the worlds of universities and think tanks, blending theoretical and practical concerns. The two major journals created during this period attempted to achieve a similar balance. Studies in Conflict and Terrorism, founded in 1977, focused on conflict resolution and security studies, seeking to apply academic research to “a unique and formidable problem of the modern world.” Terrorism and Political Violence, which followed a dozen years later, offered a less policy-oriented and more humanistic approach, soliciting work on “historical, philosophical, political, legal, psychological and cultural aspects of terrorism” even as it maintained a focus on recent events. For the most part, these pioneers adopted Hardman’s view of terrorism as a form of revolutionary revolt, a weapon of the weak against the strong. They also believed that its scope—and therefore its significance—had increased dramatically in the mid-twentieth century. Their ideas developed within a larger scholarly conversation about political violence and social movements, even as they sought policy solutions and, sometimes, accepted government funding.[8]

Within this developing field, two phenomena attracted particular concern. The first was the use of anticolonial violence by groups such as the Irish Republican Army, the People’s Front for the Liberation of Palestine, the Algerian resistance movement, and the African National Congress. The second was the lingering issue of left-wing revolutionary violence, especially by the militant youth movements spearheaded by the Red Army Faction in Germany and the Weather Underground in the United States. By studying such organizations, many researchers in the 1970s hoped to develop a general theory of terrorism, identifying which conditions give rise to violence and which do not. To a lesser degree, they also addressed the psychological dimensions of terrorism: Why did certain individuals adopted the tactic? Was there was a single terrorist personality? Most of all, they sought to underscore the illegitimacy of terrorism as a means of social change, a violation of state sovereignty and moral norms.[9]

Despite this relatively straightforward policy agenda, the field was soon mired in circular concerns and debates. Among the most maddening questions was the simplest: What is terrorism? Like Hardman, most observers emphasized that terrorism was both politics and “theatre,” in the famous words of Brian Jenkins. Countless issues nonetheless remained unresolved: How do we distinguish terrorism from other forms of warfare? Does terrorism require a random civilian target, or do assassinations of public figures count? Are acts of terrorism the product of mental deviance, or rational political acts? How much should motivation matter? How much should effect? In an attempt to reach agreement on such questions, the political scientist Alex Schmid launched a survey of the field in the mid-1980s, asking fifty social scientists to explain their views. The results identified no less than twenty-two factors that might—or might not—be necessary characteristics of terrorism. Six respondents bowed out by declaring all such efforts a hopeless waste of time.[10]

Most controversial was the issue of state terrorism. In an age of genocide and global warfare, could governments properly be classified as terrorists? Most specialists agreed that the term terrorism should be restricted to acts committed by nonstate actors—specifically, groups or individuals seeking to challenge existing governments. This limitation had the virtue of analytical consistency, making it easier to compare and contrast incidents across regions and contexts. Less fortuitously, it also reinforced the highly politicized definitions offered by governments deeply invested in discrediting rebel groups. As Noam Chomsky has pointed out, much of the back and forth over definitions was merely politics with a social science gloss. “You have to find a definition that excludes the terror we carry out against them, and includes the terror that they carry out against us. And that’s rather difficult.”[11] The issue of government funding—then as now the lifeblood of policy-oriented terrorism studies—further complicated the field. Early terrorism scholars were not, as Chomsky might suggest, mere handmaidens to power. Nonetheless, government money and institutional priorities helped shape the field’s early debates.

Despite those pressures, dissident views exerted a significant influence. Chomsky himself argued that the United States exported a state-sponsored “culture of terrorism,” especially in regions such as Central America and the Middle East. Others maintained that the most significant form of “terror” in any society—present or past—inevitably came from above. Still others lamented that the label of “terrorism” was evolving into a useless catchall for any kind of violence that governments did not happen to endorse. “‘Terrorism’ . . . has become a convenient means to identify evil threats rather than to define a special kind of revolutionary violence evolving out of Russian radicalism and European anarchism,” J. Bowyer Bell complained in late 1970s. As the field of terrorism studies expanded, the political controversy deepened.[12]

To the degree that history figured in this conversation, it served a largely negative role, underscoring the popular idea that a new and menacing force had taken root in the modern world. As Walter Laqueur noted, however, history mostly did not figure in at all. To remedy this problem, he published his now-classic study Terrorism (1977), the first major synthetic work to approach the subject from a historical perspective. In addition to surveying the dominant social science theories, Laqueur offered a sweeping tour of the global past, tracing the idea of nonstate terrorism as far back as the Zealots and tyrannicides of the ancient world. He also identified a distinct shift in the late nineteenth century, when the inchoate violence of earlier movements gave way to a systematic theory of revolutionary terror. In Laqueur’s view, modern terrorism went hand in hand with the rise of Marxism and other left-wing movements, though he also made note of considerable right-wing violence in the United States. As a historian, he was unimpressed both with attempts to expand such observations into a general theory and with the state of terrorism studies itself. “The more ambitious the project,” he noted in a summary dismissal of the field’s early efforts, “the wider its scope, the more sweeping the hypotheses, the more reckless the quantification of data, the more disappointing the results.”[13]

Despite (or because of) such criticism, Laqueur’s book provided a useful model for thinking historically about terrorism: he defined his term, then sought to trace its manifestations across various periods and locations. Over the next few decades, this approach emerged as dominant among a small but growing number of historically minded terrorism experts. Some, including Richard E. Rubenstein, Martha Crenshaw, and Bruce Hoffman, contributed compelling insights to the field, showing how changes in context reshaped the forms and efficacy of terrorist violence. In many cases, however, the new historical studies were highly selective and strangely abstruse. One so-called “historical dictionary of terrorism” listed just twenty-six ill-defined episodes of terrorism throughout the world before 1970, beginning with the Zealots, moving through Kristallnacht, and ending with the 1969 bombing of the Agricultural Bank of Milan.[14]

None of these studies, moreover, had much to say about the national experience of the United States, either as a source or a target of violence. Episodes from the country’s domestic history—the Haymarket bombing, the assassination of President William McKinley, and the rise of the Ku Klux Klan—regularly appeared in terrorism syntheses, as did a variety of international incidents involving Americans, from the airplane hijackings of the 1970s to the 1993 World Trade Center bombing. But, even into the 1990s, there was little effort to assess these events in the context of domestic political trends or even U.S. foreign policy; nor was there much attempt to integrate them into historical debates about the nature of American national identity, social conflicts, and political traditions.

This was partly because professional historians kept the subject at arm’s length, rarely engaging the policy-centered world of terrorism studies. Some of that distance resulted from methodological differences; historians, as a group, have little patience for general theories. Some resistance was likely political as well; terrorism studies tends to be seen (with only some accuracy) as the province of conservatives and reactionaries. The subjects under discussion—the theory of revolution, the history of social movements, the rise of the modern state—certainly attracted great interest within the historical profession. In the late 1960s and 1970s U.S. specialists produced an outpouring of studies addressing precisely movements cropping up in terrorism studies, from the Ku Klux Klan to the radical Left. Occasionally, historians such as Allen Trelease made the connection between the concept of “terror” and right-wing groups such as the Klan. More often, the proactive use of violence by such organizations remained a minor concern and was rarely identified as a variant of terrorism. This was particularly true in the historiography of left-wing radicalism, where New Left historians tended to minimize any association between terrorist violence and revolutionary agitation for fear of reinforcing damaging stereotypes.[15]

That trend began to change in the 1980s as the profession gained distance from the previous decades’ fraught politics. Building on his work on Russia and Europe, Paul Avrich composed pioneering studies of American anarchism, casting light onto the “darker corners,” where discussions of terrorism and violence thrived. Within labor history, Kevin Kenny reconsidered the Molly Maguires’ reputation as “terrorists,” while J. Anthony Lukas devoted more than eight hundred pages to the labor leader Bill Haywood’s arrest, trial, and acquittal for murder. In the arena of civil rights, authors such as Timothy Tyson excavated the tradition of African American armed self-defense, even while noting that “Ku Klux Klan terrorists” exercised a near-monopoly on southern violence. The Klan and other white-supremacist groups also attracted new attention, as part of a growing historiography emphasizing the importance of extralegal violence in maintaining a racial caste system. That reassessment extended into studies of right-wing and populist movements; neo-Nazis, militia members, and antiabortion militants all began to receive their due. Such attention increased in the aftermath of the 1995 Oklahoma City bombing, recognized at the time as the worst act of terrorism committed on American soil.[16]

When the 9/11 attacks occurred, then, Americans already had histories of terrorism—many of them and from a variety of perspectives. What did not exist was a coherent historiography of terrorism, a definable way to think about the role such violence has (or has not) played in the American past. It is telling, for instance, that few of the new works on anarchism, labor, the Klan, or the New Right used the word terrorism in their titles; nor was it used in their Library of Congress subject headings. Furthermore, the issue of terrorism did not play an independent role in the developing historical conversations. Terrorism as a subject was both visible and invisible, absent and present, before September 2001. What changed on 9/11 was not so much the history itself but, to borrow Hofstadter’s words, “our sudden awareness of it.”[17]

It should come as no surprise that most works on terrorism written since 9/11 have tended to focus on current events. The past decade saw an outpouring of books, of varying quality, on the subject: journalists offering elegiac accounts of bloodshed and victimization, pundits arguing about the consequences of particular acts. Their efforts complemented the rise of a formidable security-industrial complex, both private and public, constructed to carry out the “war on terror.” Although the evolution and internal struggles of such agencies as the Central Intelligence Agency (CIA), the Federal Bureau of Investigation (FBI), and the National Security Agency are beyond the scope of this essay, it is worth noting that they engage in serious debates about how to define and think about terrorism.

Within this post-9/11 boom, history remains an underdeveloped area of study. Perhaps inevitably, 9/11 sparked new historical interest in the subject, and library bookshelves now bulge with works updating Laqueur for the twenty-first century. At the same time, much recent political and intellectual debate emphasizes history’s uselessness as an analytical tool. As early as the 1990s, Laqueur himself had begun to argue that modern terrorism, with its high casualty rates and religious inflections, marked a break from the past—a form of “new terrorism,” in the social science parlance. Much of the scholarship produced since then has underscored the idea that there is something uniquely dangerous, terrifying, and utterly ahistorical about the post-9/11 world. “Substantial input by historians in the debate about the nature of terrorism has been lacking,” the Dutch scholar Isabelle Duyvesteyn noted in 2004, summarizing the state of the social science literature. “Newness,” she reminded her audience, is not simply a state of being but a matter for historical judgment.[18]

Even those inclined to take a long view in framing the 9/11 attacks as part of history rather than a break from it often find themselves inadvertently reinforcing the “new terrorism” theme. Some of the best historical work since 9/11 (much of it written by journalists) takes a limited, regional approach, exploring U.S. policy in the Middle East, the Afghan war of the 1980s, and the evolution of political Islam. Another common species of terrorism history starts at the opposite extreme of generality, offering up Laqueur-style global narratives that range widely across time and space. Both strategies have yielded some original and useful work, with the efforts of Steve Coll, Lawrence Wright, and Matthew Carr bearing special mention. But both of these approaches, perhaps perversely, also tend to reify popular narratives. The regional approach implicitly affirms a link between terrorism, Islam, and the politics of the Middle East. The more global construct often yields a teleological narrative in which all previous acts of terrorism build dramatically toward 9/11. While we learn, admirably, that terrorism has some sort of history, that history remains situated largely beyond U.S. borders and of little significance until the 9/11 attacks.[19]

For U.S. historians, efforts since 9/11 to grapple with terrorism have been far more episodic, a series of discrete interventions rather than a consistent, developing conversation. Most historians who have engaged the subject remain wedded to a particular time period and social context, shying away from broader conclusions. T. J. Stiles has argued that Jesse James might plausibly be labeled a “terrorist,” as well as a southerner, outlaw, and Confederate rebel. Ann Larabee has applied the term to the Civil War double agent Alexander “Sandy” Keith, along with the “Confederate terrorists” who conducted a guerilla war outside the official one. Historians of anarchism and labor radicalism (myself included) have used the idea of terrorism to describe particular modes of industrial warfare, offering new studies of the 1886 Haymarket bombing, the dynamiting of the Los Angeles Times building in 1910, and the 1920 Wall Street explosion. Similarly, historians of racial violence have applied the term widely, using it to describe everything from early twentieth-century race riots to the activities of the Ku Klux Klan. The Civil War scholar Michael Fellman has sought to combine all of these uses into a wide-ranging study that moves from John Brown’s abolitionist violence through Haymarket and the occupation of the Philippines, arguing that terrorism, thus broadly defined, has been a persistent and vital strain of American politics. New works on the twentieth century have applied the concept of terrorism to events ranging from Adolf Hitler’s attempted sabotage of the United States during World War II to the 1996 Atlanta Olympics bombing.[20]

What distinguishes these works is their willingness—even urgency—to engage the term “terrorism” and to contemplate how earlier events might alter contemporary understandings. Despite the shift in emphasis, however, most of the new scholarship has not broken entirely with earlier trends. With a few exceptions, the idea of terrorism still tends to emerge as a side note, a matter for prefatory comment or back-of-the-book musing. While both the word and concept of terrorism now appear more frequently and in a wide variety of books, few of those works are speaking to each other, and fewer still gesture toward any comprehensive understanding of terrorism’s role in American past.[21] If anything, 9/11 seems to have increased the number of disclaimers that accompany the word “terrorism,” as if merely using the term implies moral equivalence with Osama bin Laden. The label “terrorism” is an epithet as well as a category of analysis, and many scholars are rightly concerned that it may discredit, simplify, or otherwise misrepresent complex historical situations.

In its current uneasy state, the “field” might be said to be divided into two loose camps: those who study terrorism and embrace the term and those who study what might be labeled as terrorism but who reject the term itself. Like most hard-and-fast divides, however, these distinctions are far from absolute. Even within subfields, there is little consensus about which camp to occupy—whether one should embrace, redefine, or reject the term altogether. A notable example of this confusion can be found in the literature on John Brown, where the issue of terrorism has been added to decades of other seemingly irresolvable controversies. “Can John Brown remain an authentic American hero in an age of Timothy McVeigh, Usama Bin Laden, and the bombers of abortion clinics?” David Blight asked in 2002. The resounding answer ever since has been, well, maybe. David S. Reynolds has argued that Brown might be a “terrorist,” but a noble one. Robert McGlone similarly acknowledges Brown’s self-conscious approach to violence, but prefers the term “terroriser” as a point of distinction. The journalist Tony Horwitz, by contrast, sees little problem drawing present-day lessons from Brown’s historical example, arguing that Brown’s martyrdom provides a cautionary tale to prosecutors debating the merits of trying terrorism suspects in civilian courts.[22]

Much of the controversy in such cases tends to revolve around the issue of political sympathy. Fans of John Brown, suffice it to say, do not appreciate comparisons with Osama bin Laden. But the confusion also underscores a genuine methodological problem: How do we determine which episodes belong to the history of terrorism? For social scientists, the answer has been relatively easy: pick a definition and go hunting for past examples. That method has yielded strange and arguably ahistorical trajectories (do the Barbary pirates really have much in common with the Weathermen?). But it has nonetheless produced a coherent literature and set of conversations about where, how, and why terrorism emerged. Historians, by contrast, seem all but stymied by the methodological and political complications inherent in the term. If John Brown was not widely known as a “terrorist” in 1859, does this mean we should not use the label today? Or is it fair to apply the term retroactively, provided that the subject meets certain criteria? In that case, which definition do we choose? Should it involve state violence or nonstate violence? What should be the guiding principles for making such a decision?

In my work on the 1920 Wall Street bombing, I applied a dual test: first, did Americans in 1920 describe the event as an act of terrorism?; second, does it conform to our basic definitions of what an act of terrorism might be? The answer to both of those questions was yes, a reassuring bit of serendipity that allowed me to explore historical terrorism on its own terms. Such a strict test, however, may not always be desirable. James Green has pointed out that Americans in 1886 described the Haymarket bombing in terms of anarchism, criminality, and class conflict rather than “terrorism.” Does this mean that we too should avoid the term? Green did just that, arguing that the framework of terrorism in such a case was both anachronistic and unnecessarily pejorative. Even where the term fits more neatly, the normative problem remains. Labeling the 1920 explosion an act of “terrorism,” I often remind public audiences, does not constitute a judgment on the merits or failings of the radical challenge to Wall Street.[23]

Michael Fellman has proposed getting around such questions by adopting a broader definition of terrorism, one that encompasses state as well as nonstate violence, attacks by military forces as well as by individual bombers and vigilante mobs. This, in Fellman’s view, levels the playing field, avoiding the one-sided condemnation inherent in the term. It also places terrorism at the center of American history, converting it from a fringe phenomenon to a major factor in national politics.[24] Yet expanding the definition of terrorism poses problems of its own. No less than the wordplay of counterterrorism experts, this approach rests on certain political and moral assumptions: that governments, too, commit immoral acts, that rebels are often mislabeled and misunderstood, and that to ignore this interplay is to endorse implicitly an aggressive counterterrorist agenda. In that sense, a broader definition is no more necessarily accurate or “historical” than a more limited one; it simply expands the scope of inquiry.

Given the already-fractured state of the literature, this more expansive approach may not be desirable—a lurch toward incoherence rather than common understanding. Alternately, it may simply be premature. After all, we do not yet have a full understanding of the role that nonstate terrorism has played in the American past or of how the United States might fit in the global framework crafted by social scientists and journalists in recent years. Drawing on this more established literature, the remainder of this essay attempts to sketch out a tentative narrative of American terrorism and to suggest areas for future research.

Any history of terrorism is really two histories, if not more. The first is what we might call an “internal” story, a tale of how various groups and individuals, with different backgrounds and ideologies, have conceived of terrorism as a tactic. The second, or “external,” narrative concerns the response of the state and society to such challenges, whether in cultural, political, or social terms. Perhaps surprisingly, most histories of terrorism focus on the former story, tracing commonalities in strategy and self-conception across a range of centuries and contexts. For historians concerned with how terrorism and political violence have affected national politics, however, the latter narrative is arguably more important. Precisely why the internal history has received so much more attention than the external—why, for instance, we know almost nothing about the history of counterterrorism policy or official definitions before the 1990s—is itself worthy of contemplation. Despite the decades-old call to “bring the state back in,” perhaps the dissident rebel still holds greater allure as a subject of study than the elite policy actor.

In their search for a point of origin, most general histories of terrorism begin either in the ancient world or the late nineteenth century. Despite that initial variation, almost all follow the same general trajectory once they reach the twentieth century, identifying several distinct forms of modern terrorism that have evolved in conversation with each other. In an influential 2004 essay, the religion scholar and political scientist David Rapoport described these forms as the “four waves” of modern terrorism: the “Anarchist Wave,” stretching from the 1880s through 1914; the “Anti-Colonial Wave,” spanning the 1920s through the 1960s; the “New Left Wave,” from the 1960s through the 1990s; and the “Religious Wave,” which began with the 1979 Iran hostage crisis and persists to this day.[25]

How does the United States fit in this picture? By certain measures, these categories capture the American experience tolerably well. But if the study of terrorism teaches us anything, it is the difficulty of studying the United States in isolation from the rest of the world. Any serious history of terrorism, even within a national framework, must by definition adopt a transnational perspective, incorporating an understanding of global population flows and social movements into its story. This is especially true, though perhaps not entirely obvious, during the so-called first wave of anarchist terrorism, when the United States was well known as a haven for revolutionaries fleeing persecution in Europe.26 It is similarly true of the latter half of the twentieth century, when the United States emerged not only as a victim but also as an architect and financial supporter of transnational terror. The history of terrorism deals yet one more blow to American exceptionalism, showing that the United States has never stood entirely alone on matters of violence, rebellion, and political conflict.

From a Eurocentric perspective, starting with an anarchist wave makes a great deal of sense. Yet it is not clear that this is the appropriate place to begin a discussion of terrorism in the United States. Many earlier types of violence lend themselves to an intuitive link with the concept of terror. Massacres of Native Americans, for instance, were violent, political, planned, communicative, and carried out beyond the auspices of the formal state—the basic criteria used by the terrorism scholar Bruce Hoffman in his attempt to pin down a definition. For a nation born of revolution and guerrilla warfare, an equally compelling starting point might be the War of Independence. Perhaps George Washington, not Alexander Berkman, was America’s first terrorist. At the very least, as Fellman points out, it seems inappropriate to leave out the trajectory of political violence that led from John Brown to the Civil War to the brutal clashes of Reconstruction. Ann Larabee has argued that the Civil War produced both the technology and the training that made postwar terrorism possible. The relationship between war and terrorism remains one of the most promising, complex, and understudied areas in the developing historiography.27

Whether or not the rise of anarchist and revolutionary violence in the latter half of the nineteenth century marks the sole starting point, it does seem to constitute a significant turning point in the United States as elsewhere. The mid-nineteenth century brought the rise of dynamite and other modern explosives, technological innovations that improved the ability of revolutionaries to strike anonymous blows from afar. In addition, as Hardman noted in the 1930s, revolutionary movements around the world began to develop the first full-fledged theories of terrorism. Today, we tend to think of terrorism as a secretive, hidden, and particularly irrational tactic, rarely conceived in terms of logic or strategic aims. But its nineteenth-century practitioners were surprisingly open in discussing the tactic’s virtues and pitfalls and in fostering their own definitional debates. Their conversations, in turn, led to changes in public discourse, as police and government officials began to seek labels for the revolutionary threat in their midst. It was in the late nineteenth century, in short, that technology, theory, and political discourse combined to produce something recognizable as modern terrorism—the basis for Rapoport’s framing of this era as a first wave.

While the idea of an anarchist or revolutionary wave describes certain aspects of the U.S. experience, the chronology of American violence differed somewhat from its European counterpart. According to most global histories, anarchist violence reached its zenith in the 1890s, the so-called age of regicide, during which assassinations and bombings attracted widespread police attention throughout Europe. In the United States, however, the bloodiest violence occurred decades later, during and after World War I. In addition, most of the violence accompanying American industrial development occurred not in highly staged attentats by anarchists and revolutionaries but through armed warfare along the picket line, where strikers often faced off against soldiers, private guards, and detectives. It is worth asking how much of the violence in American labor conflict, either from above or from below, ought to be included under the label of terrorism. Does the dynamiting of the Los Angeles Times building count? Does the 1914 Ludlow massacre? Who, in either case, were the real terrorists?

Equally pressing issues emerge from the history of American racial conflict, the single most widespread type of politicized violence in the nation’s past and the most notable absence in Rapoport’s global chronology. Many histories of terrorism mention isolated instances of racial violence in the United States. Nowhere, however, does this anecdotal evidence transform any larger chronological framework or suggest new ways of considering the issue. This is perhaps because such violence, as Hofstadter pointed out, is “diffuse and hard to cope with.” The Reconstruction-era Klan certainly meets any garden-variety definition of a terrorist organization; its actions were nothing if not violent, political, well planned, and intended to communicate a message. The case becomes somewhat less clear, however, by the late nineteenth century, when spectacle lynchings and so-called race riots emerged as enforcement mechanisms for the developing system of Jim Crow. In making his case for reparations, the Harvard University law professor Charles Ogletree has described the 1921 Tulsa race riot as “the most tragic example of domestic terrorism in America’s history.” His point is rhetorical, intended to underscore the horrors inflicted on African Americans. But there is also an analytic and interpretive issue at stake in the choice of such terms. Using the word terrorism highlights the deeply political and deliberate nature of racial violence, refuting arguments (once presented to sympathetic juries) that lynchers or rioters were simply caught up in a frenzy of outrage.28

It also underscores one of the most fascinating and revealing contradictions in the “external” story of terrorism. Beginning in the 1880s, bombings attributed to anarchists or labor activists often served to justify widespread campaigns of suppression against radical movements. Lynchings and race riots, by contrast, generally met with inaction, even approval, in official circles. Including those forms of violence in a national narrative of terrorism can help underscore the cultural context in which decisions about how and why to react to terrorism have occurred. Their inclusion also discredits the notion that the mere fact of violence necessarily produces a swift and active government response. Normative judgments, not simply law enforcement strategy, have long shaped how and if acts of terrorism become national emergencies.

Like revolutionary terrorism, which began to fade by the mid-1920s, racial violence underwent a shift in the interwar decades, moving from open, spectacle lynchings to forms of clandestine violence—bombing attacks, premeditated murders—more easily recognizable as variants of terrorism. Figuring out why the forms of violence changed as they did marks yet another endeavor in which historians and terrorism scholars might benefit from a more robust conversation. Charles Payne, for instance, has suggested that lynching lost its efficacy when the southern cotton economy began to collapse and the federal government took a greater interest in preventing violence. He also notes that such government interest would have mattered little if ordinary people had not organized to defend themselves against violence and transform their political situations. In this case as in others, a historical approach to terrorism highlights what other methodologies cannot: why certain forms of violence flare up and then disappear.29

What followed the anarchist wave, in Rapoport’s telling, was the age of anticolonial terrorism (1920s–1960s), characterized by nationalist uprisings around the world. This violence differed from that of earlier episodes, according to the standard story, in at least two important ways. First, terrorism against civilians emerged in the context of anticolonial conflicts often dominated by more conventional military tactics. Second, the practitioners of terrorism made direct claims on territory, seeking to become the governing class. The classic example is Algeria, where bombs in civilian cafés complemented an indigenous guerrilla struggle aimed at driving out the French occupying authorities.

Notably, the United States gets short shrift in most global overviews of this period. With the exception of episodic attacks by Puerto Rican nationalists, the United States remained relatively insulated from the anticolonial surge, at least in terms of violence committed on American soil. The relative absence of terrorism as an issue in U.S. domestic politics during these years underscores the peculiar nature of American empire, with its preference for temporary occupation over direct annexation. It also heightens the contrast with later decades, when Americans gradually became accustomed to thinking of themselves and their institutions as targets for international attack. Finally, it obscures the often-aggressive role of the U.S. government in fostering what was arguably “terrorist” activity abroad, especially through the Cold War–era CIA.

The reprieve on the domestic front came to an end in the 1960s when Americans experienced a major comeback of terrorism on U.S. soil. Some of the earliest violence of the decade looked remarkably similar to previous episodes: Klan dynamitings, lynchings, and assassinations aimed at civil rights workers and African Americans. The question of how to respond to such violence is one of the most complex and fascinating areas of civil rights history. Many historians have shown how the nonviolent civil rights movement absorbed and advertised repressive violence to rouse the national conscience and spur federal action. They have noted as well the uneasy transition in both the civil rights and antiwar movements from nonviolence to armed resistance. In U.S. historiography this shift is often described in domestic terms, as a declension narrative of American liberalism or a tale of how the Vietnam War ultimately provoked violence at home. But as the historian Jeremy Varon has argued, it is at least as compelling to view rising New Left militancy in international terms, as part of a global revolutionary conversation on the merits of terrorism, armed resistance, and urban guerrilla warfare. “New Leftists were not only implicitly united across national boundaries by their shared opposition to oppression, their commitment to democratic participation, and their use of militant direct action as a means of protection;” he writes, “they were also consciously internationalist.”30

Seen from that perspective, the United States’ narrative fits neatly into Rapoport’s global New Left wave, beginning in the 1960s and stretching into the 1990s. Yet in the case of the United States the implications of the “New Left” label are somewhat misleading. Throughout most of the twentieth century, right-wing terrorism has more than matched the violence of the Left; even at the height of “New Left” activity, the Klan was a far more significant force than the Weather Underground. Why then does right-wing violence play such a minor role in the literature on terrorism? Part of the answer is political. Reactionary violence tends to attract less attention from government officials and therefore attracts less attention from terrorism experts. But some of the answer may lie in the nature of the violence itself. Modern right-wing violence, whether perpetrated by the Klan or the likes of Timothy McVeigh, has often focused on domestic issues, while the Left, as Varon points out, asserted a more self-conscious internationalism. As a result, histories of terrorism oriented toward the global story tend to underestimate the significance of right-wing terror, a hole that U.S. historians might seek to fill.

Globally, the most significant strain of terrorism to emerge as a policy concern during the 1960s came from the Middle East, a by-product of the 1967 Arab-Israeli war. Bruce Hoffman identifies the hijacking of an El Al flight in July 1968 as the founding moment for “modern, international terrorism,” the day that Palestinian militants expanded the scope of their tactics—from making direct attacks on the Israeli government to bringing their fight to the rest of the world. He sees this as a turning point between anticolonial terrorism, conducted mainly in the territory under contest, and international terrorism, which targeted representatives of Western power wherever they might be. In the United States, however, it is not clear that this period marks a significant turning point. In the 1970s, U.S. officials appeared to view terrorism as a minor annoyance within the larger Cold War struggle. It remains difficult to say anything definitive about U.S. counterterrorism policy during these years. In 2005, acting under the auspices of the 9/11 commission, Timothy Naftali assembled the first historical survey of U.S. counterterrorism policy in the twentieth century, beginning in the 1950s and moving through the harried debates of 2001. Since then, however, just a handful of works, most of them written from a policy perspective, have attempted to fill in the gaps. This relative neglect seems striking given the subject’s obvious relevance for contemporary politics. It is a promising area of study that younger scholars will hopefully embrace.31

We know, for instance, that President Jimmy Carter described the Iran hostage crisis as an act of terrorism, but what did he intend to convey with such a designation? Was it a vague term of moral outrage? Did it carry particular legal and diplomatic penalties? Was it an attempt to delegitimize all violence stemming from the Middle East? For that matter, how did the U.S. government sort out which groups might be designated as terrorist organizations? How did it attempt to avoid having such labels assigned to its own actions in proxy wars? As Chomsky noted, Cold War alliances often made even the pretense of consistency a tortured affair for policy makers. This was a particular problem in places such as Central America, where the United States covertly sponsored squads engaged in widespread acts of violence against both left-wing governments and the population at large. It was also an issue in Afghanistan, where the United States supported the mujahedeen resistance to Soviet occupation in the 1980s. 32

In the social science literature on terrorism, both the Iran hostage crisis and the rise of the mujahedeen are deemed exemplars of a trend—pioneers in “new terrorism” or, in Rapoport’s construct, part of the religious wave. Like its New Left predecessor, the “religious” or “new terrorism” framework encompasses both domestic and international violence—in the case of the United States, this means both Timothy McVeigh and Osama bin Laden. The sociologist Mark Juergensmeyer made that connection well before 9/11, traveling the world to interview abortion clinic bombers, members of the Irish Republican Army, and Japanese cultists, as well as Zionist, Sikh, and Islamist assassins. He concluded that what mattered in each case was a cosmic, apocalyptic outlook divorced from particular political objectives. “All these instances share two striking characteristics,” he wrote. “First, they have been violent—even vicious—in a manner calculated to be terrifying. And, second, they have been motivated by religion.”33

As Isabelle Duyvesteyn has pointed out, that emphasis on religion tends to obscure the political nature of much recent terrorism. Groups such Al Qaeda, she suggests, might better “be seen as political and religious at the same time.”34 Domestically, a similar equation holds true: Timothy McVeigh may have purported to love Christ, for instance, but he also despised the federal government. One of the most valuable contributions historians might make to the study of terrorism is to question whether the labels of “new” and “religious” terrorism are indeed accurate, and if so, in what ways. Historians might also challenge assumptions behind such labels, especially the ways that “religious” has become a proxy for “irrational,” while “political” seems to suggest rational, manageable, and achievable aims. Certainly, the 9/11 attacks killed a greater number of people than many previous acts of political violence and spurred a far more dramatic state reaction. But the tactic was not entirely new; nor was the nature of the social and political response.

The increasing tendency to push politics out of the discussion of terrorism is itself a political act and one that, purposely or not, tends to license extreme government behavior. If your opponents are religious fanatics who will stop at nothing to achieve their ends, the “new terrorism” logic suggests, then the government has little choice but to do the same.35 How we think about the relationship between terrorism and history, then, is not merely a matter for scholarly debate. It is also an issue with important implications for the present day. The idea of a religiously based “new terrorism” suggests that the past has nothing to offer, that we must start by abandoning all strategic and cautionary knowledge. To think historically, by contrast, is to insist that we might, after all, have something to learn. This essay concludes by revisiting the links between past and present and suggesting what a few of those lessons might be.

As with any emerging subfield, the mission itself is the message. What we learn from studying the history of terrorism is that terrorism has a history, even within the United States. This should perhaps be obvious, but much of the political rhetoric since 9/11—the day when “everything changed”—has suggested otherwise. Even scholars who study the issue seem less than convinced of the importance of terrorism’s history in the U.S. context. “Contrary to the conventional wisdom widely accepted during the 1980s and 1990s—and even now after the 9/11 attacks,” reads a 2007 terrorism survey, “the United States was not completely spared the phenomenon of terrorism in the course of its history, although it may be said that until now terrorism never had a significant impact on the country’s political and social life.”36 The persistence of this narrative suggests that U.S. historians have not been nearly as successful as Hofstadter predicted (and as the historical profession might believe) in putting violence at the center of American history. It also underscores one of the great ironies in studying the history of terrorism. At least since the Haymarket bombing in 1886, Americans have been losing their innocence on the subject, discovering that the United States is not exempt from political violence on its own soil. The claim that terrorism does not have a history or presence in the United States, in other words, has a long history of its own.

Like the idea of “newness,” assertions about terrorism’s absence, or its foreign nature, have long served political agendas. In the late nineteenth century, elite commentators often explained anarchist violence as a European importation, suggesting that class and revolutionary conflict were antithetical to the American experience. Today, political leaders use the words “terrorism” and “terrorist” almost exclusively to refer to international networks and threats. By contrast, native-born white Americans who commit acts of political violence are usually treated as misguided individuals.

Taking a historical view of terrorism begins to break down these accepted binaries. Terrorism, history tells us, has come both from without and from within, and it has emerged in a variety of political contexts. The historical approach also underscores the connections between the highly varied political actors who have, at one time or another, adopted some variant of terrorism as a tactic of vengeance or political gain. Seen from a historical perspective, terrorism has almost never emerged in a political vacuum. Whether in Harpers Ferry or Oklahoma City or downtown New York, dramatic acts of violence have tended to erupt in the context of much broader political and social conflicts. Those larger conversations—about slavery, plutocracy, or U.S. tyranny—give such acts of violence their communicative power. It goes almost without saying that terrorism has often sparked official repression, often at great cost to the movements or causes for which the act was purportedly committed. It is somewhat less obvious—and certainly less comforting to acknowledge—that terrorist violence also often achieves its aim of disrupting the status quo and drawing attention to a cause. Practitioners of such violence have rarely been able to control the effect of their acts, but if terrorism never had any “positive” outcomes from the perpetrators’ perspective, surely these violent tactics would have neither lasted nor escalated.

Perhaps surprisingly, the emerging historical literature suggests commonalities in the ways that practitioners of terrorism have articulated and justified their goals, regardless of time period or political context. Often, for instance, they claim a defensive position, arguing that their own violence merely highlights the ongoing violence of the existing social order. At its worst, noting such similarities can lead to a flattened and ahistorical analysis of the “terrorist mind-set” or “terrorist personality.”37 At its best, though, drawing such connections can help shake up present-day assumptions about the “newness” of contemporary strategies or about terrorism’s exclusive ties to the Middle East. It can also identify genuine historical continuities, including the ways that individuals and groups have learned from past examples and constructed their own genealogies of violence. We know, for instance, that the anarchist movement, the Weathermen, the antiabortion movement, and Timothy McVeigh all claimed the mantle of John Brown. And each, in turn, adopted the banner of the American Revolution. Though Americans prefer to think of terrorism as a foreign phenomenon, it might be more accurate to say that the United States has its own terrorist tradition.

If the perpetrators of violence seem to have learned from past examples, so too has the state. Both the institutions and the ideas that govern our current war on terror have deep historical roots. The FBI, for instance, began its history of political surveillance in response to fear of terrorism, violence, and social disorder during and after World War I. Similarly, the use of immigration and deportation law to deal with violent threats has a long, dubious past. Some of the best work on such issues comes from the literature on free speech and civil liberties, where scholars have traced a careful evolution from the 1919–1920 Palmer raids through the war on terror. That literature, however, tends to underestimate the problem of violence itself, as if speech had little relation to acts and as if state actors rarely had genuine threats to consider. Developing a more robust understanding of terrorism’s history can help contextualize the decisions made by state actors, from judges to presidents to law enforcement and immigration officials.38

It may also help provide guidance for today’s policy makers. Contending with the “lessons of history” is almost unavoidable in a ripped-from-the-headlines subject such as terrorism. It is tempting to draw tidy conclusions about how to contain further violence: the Palmer raids show the perils of unrestricted deportation raids; the FBI’s dismantling of the Ku Klux Klan reveals the importance of undercover intelligence work. These are undoubtedly useful contributions to worthwhile policy debates. Yet the larger historical record suggests that such particulars will not be the critical factors in bringing our own age of terrorism to a close. Overwhelmingly, the phenomenon of terrorism has waxed and waned along with larger movements and debates, less a law enforcement problem than a symbol—or symptom—of greater conflicts. This should be heartening to historians, vindicating the idea that violence cannot be understood absent a deep sense of social and political context. It should be somewhat more alarming—or at least frustrating—to policy makers focused on the limited agenda of counterterrorism. If there is a major lesson to be learned from studying terrorism historically, it is that strategies aimed at containing violence will likely fail without attention to resolving the political and social conflicts at stake.

The essential point of historical inquiry, of course, is not to intervene in contemporary debates or to learn lessons, sins that historians learn to denounce as “presentism” in their first days of graduate school. Yet too rigid an adherence to such strictures can lead to obscurantism and disengagement, as if historians have nothing to say about the day’s most pressing social questions. The historiography of terrorism, with its uneasiness about terminology, its political uncertainties, and its fractured discussions, is still struggling to find the proper balance between these imperatives. But as Hofstadter suggested half a century ago, such tensions often produce the most fruitful results. “I know it is risky,” he admitted in 1960, a decade before his essay on violence, “but I still write history out of my engagement with the present.”39 For the emerging historiography of terrorism, the rewards are well worth the risk.