Figure 2. Trajectories of Attacks on the United States of 53 Anti-US Terrorist Groups 1970–2004
Source: LaFree, Yang, and Crenshaw (2009).
As these data have been assembled, we have been able to develop a more accurate picture of trends in terrorist attacks in the United States over the past four decades. In Figure 3, we show a map of total terrorist attacks in the United States from 1970 to 2010. The dots are proportional to the number of events taking place in specific areas (larger dots representing a high frequency of events). Figure 3 shows the concentration of attacks in big cities, with clearly visible clusters in New York City, Washington, DC, Miami, San Francisco, and Los Angeles. In fact, nearly 30 percent of all attacks took place in one of these five metropolitan areas. The same general pattern holds true for just those events that produced
fatalities: a small portion of metropolitan areas account for a large portion of total attacks. San Francisco had the largest number of fatal attacks (n 5 22, 9.9 percent), followed by New York City (n 5 15, 6.8 percent), Los Angeles (n 5 12, 5.4 percent), Miami (n 5 10, 4.5 percent), and Washington, DC (n 5 8, 3.6 percent). At the same time, it is interesting to observe that every single state in the United States has at least one attack during the past forty years. Figure 4 shows trends in US total and fatal attacks from 1970 to 2010. Perhaps the most striking feature of Figure 4 is the dramatic decline in US domestic terrorism over time. Attacks were most common in 1970 with over 450 per year. After steep declines
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in the early 1970s, attacks reached a secondary peak of 142 in 1975. Attack rates again declined throughout the end of the 1970s and early 1980s, falling below fifty attacks per year for most years. Interestingly, the total number of domestic attacks since 9/11 has generally been lower than at any other period during the past forty years. The most active groups in the 1970s were the New World Liberation Front and the Fuerzas Armadas de Liberación Nacional. The most active groups in the 1980s were anti-abortion extremists and the Jewish Defense League. The most active groups in the 1990s were again anti-abortion extremists and the World Church of the Creator. And the most active groups since 2000 have been the Earth Liberation Front and the Animal Liberation Front. It is also clear from Figure 4 that total attacks are strongly correlated with fatal attacks (r 5 .72, p .01). Thus, the number of fatal attacks decreased rapidly after the early 1970s, from a high of twenty-five in 1970 to a low of seventeen for the first decade of the twentyfirst century. However, the most deadly groups for attacks against the United States have been quite different from the most active groups. Thus, in the 1970s, the most deadly groups were the Black Liberation Army and the Death Angels. The most deadly groups in the 1980s were the Posse Comitatus, the Justice Commandos for the