The annual chance of being murdered in a foreign-born terrorist attack in the United States was about 1 in 4.5 million during the 1975–2023 period, according to my new policy analysis published by the Cato Institute. During that time, 230 foreign-born terrorists murdered 3,046 people in attacks on US soil.

The 2,979 people killed in the 9/11 attacks account for almost 98 percent of all people killed in foreign-born terrorist attacks during that timeframe. Since 9/11, 44 people have been killed by foreign-born terrorists in domestic attacks. The annual chance of being murdered in a non-terrorist homicide is about 323 times as great as in a foreign-born terrorist attack during the entire period.

My analysis counts the visas that the terrorists had upon entry to the United States, which is where the immigration-security failure occurred. Terrorists who entered on tourist visas are responsible for 93 percent of the murders because 18 of the 19 9/11 hijackers entered on tourist visas. Five percent were murdered by terrorists on student visas, mainly because one of the 9/11 hijackers entered on a student visa. Terrorists who entered on other types of visas all account for less than one percent of the murders committed in foreign-born terrorist attacks.

Illegal immigrant terrorists murdered zero people in attacks.

Figure 1 shows the annual chance of being murdered by a foreign-born terrorist based on the visa he used to enter the United States. There are two zeros in Figure 1 because my analysis includes terrorists who attempted attacks, were thwarted, or whose attacks did not murder anyone. I do not include the deaths of terrorists in the body count.

Terrorism is the threatened or actual use of illegal force and violence by a nonstate actor to attain a political, economic, religious, or social goal through coercion, fear, or intimidation. In modern debates, one often hears people label especially heinous or persistent criminals as “terrorists.” But this doesn’t make much sense unless you think terrorism is just a synonym for “really bad crime.” It isn’t.

Thus, terrorists have religious or other ideological motivations for their attacks that are different than the motivations for most other crimes. Unsurprisingly, terrorists motivated by Islamism account for 3,028 of the murders committed in the US by foreign-born terrorists, or about 99.4 percent. Islamist terrorists also comprised 66.5 percent of all foreign-born terrorists.

It was challenging to separate hate crimes from terrorism, but I did my best. If you think I missed any foreign-born terrorists, please look at the Appendix and let me know.

My new paper is an update of older papers I wrote on the same topic. An interesting tidbit lost in the analysis is that most foreign-born terrorists don’t kill anyone in terrorist attacks. Of the 230 foreign-born terrorists, 76 percent did not manage to murder anyone in their attempted, planned, or actual attacks. Figure 2 includes the distribution of murders by individual terrorists. Outside of the 9/11 hijackers, Tashfeen Malik was the deadliest foreign-born terrorist who murdered 14 people. She and her US-born husband murdered 14 people in an attack in San Bernardino, California, on December 2, 2015. I credited Malik with all the murders, as I did with all attacks involving a foreign-born terrorist and a native-born American, to bias the analysis against the foreign-born and thus blunt criticism.

Figure 2

Murders by Individual Terrorists and Their Distribution

Updating my data on terrorism takes an enormous amount of research, including reading Department of Justice press releases, court documents, news reports, government analyses, reports by other researchers, and much more. Thousands of pages and more hours than I can count. So why do all this work when the results are about the same every year? Because the political debate over immigration spends an excessive amount of time worrying about the hazard posed by foreign-born terrorism. Foreign-born terrorists pose a threat, and terrorists could cross the border as illegal immigrants to kill Americans.

However, the threat is low compared to normal crime, other hazards, and other ways foreign-born terrorists enter the country.

Furthermore, the government has spent trillions of dollars on anti-terrorist activities here and abroad to reduce an already small risk even further. That misallocation of resources kills people directly through foolish foreign wars and indirectly by changing individual behavior, to say nothing of the waste of taxpayer dollars, our diminished civil liberties, and the deadweight loss from increased immigration restrictions.

Facts aren’t sufficient to produce better public policy, but they are often necessary. The facts in my policy analysis should help.