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Trends in terrorism in the U.S.: New report analyzes terrorist attack data 1970-2011

The most common weapons used in the 207 terrorist attacks in the United States from 2001 to 2011 were incendiary devices and explosives, according to a new report from the National Consortium for the Study of Terrorism and Responses to Terrorism. For the entire duration covered by the study, 1970 to 2011, these two categories accounted for more than 81 percent of all the weapons used in the attacks.
Incendiary devices accounted for more than half of all weapons used over the last decade, representing a large increase in the use of such weapons compared with the norm for the 1970 to 2011 time period. However, from 2001 to 2011, the use of explosives such as dynamite, grenades and "car bombs," is markedly lower, accounting for only 20 percent of all weapons used compared with 52 percent for the entire sample from 1970 to 2011.
Firearms were used less often in terrorist attacks in the United States than they were in other parts of the world. In START's Global Terrorism Database (GTD) as a whole, which currently includes information on more than 104,000 terrorist attacks from around the world, 38 percent of all of the weapons used in terrorist attacks between 1970 and 2011 were firearms while firearms represented about 13 percent of the weapons used in U.S. terrorist attacks for the same time period. In general, the most commonly used firearms involved readily available types, including shot guns and pistols.
The new report focuses on the U.S. segment of START's GTD and describes trends at the country, state and city levels, among the 2,608 terrorist attacks occurring in the United States between 1970 and 2011. Throughout that time period, the frequency of terrorism has generally decreased drastically and fatal attacks are much less common than non-fatal attacks.
In focusing on the data on attacks occurring between 2001 and 2011, the authors found:
  • There were 21 fatal terrorist attacks in this time period.
  • Total attacks declined from a high of 40 in 2001 to nine in 2011.
  • From 2001 to 2011 California (40) and New York (19) experienced the most total terrorist attacks against the U.S. homeland.
  • The three cities in the United States that experienced the most attacks from 2001 to 2011 were New York City (12), Washington, DC (9) and Los Angeles (8).
  • The most common targets of terrorists in the United States during this time period were businesses (62 attacks), private citizens and property (59 attacks) and government (43 attacks).
  • The three terrorist organizations with the largest number of attacks on the U.S. homeland from 2001 to 2011 were the Earth Liberation Front (50), the Animal Liberation Front (34) and al-Qa'ida (4).

Additionally, the GTD includes incidents involving perpetrators who were "out the door" intending to imminently attack their targets but who were ultimately unsuccessful. The study found that the highest proportion of unsuccessful attacks since 1970 occurred in 2011, when four out of nine recorded attacks were unsuccessful. The lowest proportion of unsuccessful attacks occurred in 1990 when all 31 attacks in the United States were successful.

The study was funded through START by the Department of Homeland Security, Science and Technology Directorate's Resilient Systems Division.

The full report, "Integrated United States Security Database (IUSSD): Data on the Terrorist Attacks in the United States Homeland, 1970 to 2011," is available at http://www.start.umd.edu/start/publications/START_IUSSDDataTerroristAttacksUS_1970-2011.pdf.