At an August 12th “Unite the Right” rally in Charlottesville, Virginia, Nazi-sympathizer James Alex Fields Jr. allegedly drove his car into a group of counter-protesters and murdered Heather D. Heyer. In the aftermath, virtually all commentators condemned the attack and the ideology that inspired it. But then some partisan commentators began to argue that Antifa, a self-styled group of anti-fascist protesters who want to beat up Nazis, were also inciting violence at Charlottesville.

There are certainly plenty of Left Wing thugs and terrorists, but there have not been many attempts to compare them to other ideologically-inspired terrorists who have committed murder on American soil, until my recent Cato Institute blog on the subject.

Information on terrorist attacks and the terrorists themselves in the United States is available from the Global Terrorism Database, the RAND Corporation, and other sources. I further grouped the ideology of the attackers into four broad categories of Left Wingers, Nationalists and Right Wingers, Islamists, and Unknown/​Others.

Terrorists murdered 3,342 people on U.S. soil from 1992 through August 12, 2017. Islamist terrorists are responsible for 92% of all those murders. The 9/11 attacks, by themselves, killed about 89% of all the victims during this time. During this time, the chance of being murdered in a terrorist attack committed by an Islamist was about 1 in 2.5 million per year.

Nationalist and Right Wing terrorists are the second deadliest group by ideology, as they account for 6.6% of all terrorist murders during this time. The 1995 Oklahoma City bombing, the second deadliest terrorist attack in U.S. history, killed 168 people and accounted for 77% of all the murders committed by Nationalist and Right Wing terrorists. The chance of being murdered in a Nationalist or Right Wing terrorist attack was about 1 in 33 million per year.

Left Wing terrorists killed only 23 people in terrorist attacks during this time, about 0.7% of the total number of murders, but 13 since the beginning of 2016. Nationalist and Right Wing terrorists have only killed five since then, including Charlottesville. Regardless, the annual chance of being murdered by a Left Wing terrorist was about 1 in 330 million per year.

Terrorists inspired by Nationalist and Right Wing ideology have killed about 10 times as many people as Left Wing terrorists since 1992. Terrorists with unknown or other motivations were the least deadly. Islamists swamped them all.

There is some ambiguity in counting terrorist attacks by ideology, but only with a minority of deaths. Islamists and unknown/​other terrorists are easy to categorize. Left Wing terrorists included communists, socialists, animal rights activists, anti-white racists, LGBT extremists, attackers inspired by Black Lives Matter, and ethnic or national separatists who embrace Socialism. Nationalist and Right Wing terrorists include white nationalists, neo-Confederates, non-socialist secessionists, anti-communists, fascists, anti-Muslim attackers, anti-immigration extremists, sovereign citizens, bombers who targeted the IRS, militia movements, and abortion clinic bombers.

My terrorism research focuses on deaths committed by terrorists because that is the easiest and the least ambiguous metric to analyze the damage committed by terrorism. Attacks could be as minor as a pipe bomb left by a bulldozer that explodes at 2:30 a.m., or as deadly as the 9/11 attacks that killed 2,983 people and caused billions in property damage, so counting the number of attacks by ideology does not reveal much.

The risk of being killed in a terrorist attack on U.S. soil is small. The chance of being murdered in a non-terrorist homicide from 1992 through 2017 was about 1 in 17,000 a year, which is about 133 times as great as being killed by a terrorist. Islamist terrorists are the deadliest in U.S. history—and certainly since 1992. Islamism is an ideology created overseas, while much of the ideology that inspires Nationalist, Right Wing, and Left Wing terrorism is homegrown.

The number of people killed in terrorist attacks on U.S. soil is small, but some ideologies inspire more terrorism than others. Islamists have killed about 14 times as many people as Nationalist and Right Wing terrorists who, in turn, have killed about 10 times as many people as Left Wing terrorists. Keeping these numbers in perspective should help cut through the partisan spin after the Charlottesville terrorist attack.