The odds of dying in a terrorist attack committed by an immigrant who entered on a green card during that time are about one in 723 million per year. This number even exaggerates the danger to American citizens and legal immigrants. If you do not include the deaths of the six out of eight people murdered by Saipov on Halloween who were Argentinian tourists, the danger to American citizens decreases even further, to about one in 1.2 billion a year.

That miniscule probability merits a comparison to far‐​more routine dangers. About 800,000 people were murdered in nonterror homicides during the 43‐​year period I studied. That means your annual chance of dying in a normal homicide is about one in 14,000 a year — about 50,000 to 80,000 times more likely than being killed in a terror attack committed by a green card recipient.

More than three times as many people are murdered each day in the United States than the total number who have been murdered by foreign‐​born terrorists during the last 43 years. Every death in a terrorist attack is a tragedy, and life cut short should be punished under the law, but let’s not exaggerate the danger.

Still, the public fears terrorism and might fall for the administration’s scare tactics. According to a June 2017 Gallup poll, 42 percent of Americans are very worried or somewhat worried that they or a member of their family will become a victim of terrorism. The same poll showed that about zero percent of Americans actually knew a victim of terror.

However deep fear of terrorism runs, Americans don’t support any major changes to public policy because of that threat. A December 2017 Pew poll found that 80 percent of Republicans and 61 percent of Democrats believe that the federal government is doing a good or somewhat good job of keeping the country safe from terrorism.

The government needs to have a good reason to permanently separate American citizens from their foreign‐​born family members. As tragic as recent terror attacks have been, the danger posed by foreign‐​born terrorists entering using green cards does not justify the pain and anguish that will come from separating American citizens from members of their family born overseas. In all of these cases, the Trump administration is going after the wrong people.