Another terrorist attack. Another grim tally of the dead and wounded. Another killer full of hate, from a land that breeds such men. Like millions of migrants before him, the perpetrator crossed the border unchallenged. And like others, he struck our country without warning.

Our politicians say they’ll stop these killers. They talk about building walls and vetting refugees. If we were serious, we would do it. We would seal our borders against North Carolina.

North Carolina? It sounds absurd. When we think about immigration and terrorism, we think of Syria. But that’s not where our casualties are coming from. On Friday, a gunman killed three people and wounded nine more at a Planned Parenthood clinic in Colorado. The suspect is white American Robert Lewis Dear. When police apprehended Dear, he uttered one telltale phrase: “no more baby parts.” People who have known or met Dear say he wasn’t a regular churchgoer. But they also report that he believed devoutly in the Bible and that he claimed to have read it “cover to cover.” In an online forum, Dear apparently spoke of Jesus and the “end times.” He painted or posted crosses on at least three of his homes.

Dear moved to Colorado last year from North Carolina, where he had been living. For two decades, the Tar Heel State has been a hotbed of religious extremism, fueled by clerics who preach holy war. The result is a stream of interstate terrorism.

It began with Eric Rudolph, a Holocaust denier who grew up in the Christian Identity movement. In 1996, Rudolph traveled from North Carolina to Atlanta, where he detonated a bomb at the Olympics, killing one person and injuring more than 100 others. A year later, Rudolph bombed a lesbian bar in Atlanta, wounding five people. In 1998, he bombed a reproductive health clinic in Birmingham, Alabama, killing a security guard and injuring a nurse. The “Army of God,” which hosts Rudolph’s writings, claimed credit for his attacks.

In 2001, Steve Anderson, another Christian Identity follower, was pulled over for a broken tail light on his way home from a white supremacist meeting in North Carolina. He pumped 20 bullets into the officer’s car and fled. Police found weapons, ammunition, and explosives in his truck and home. A year later, he was captured in the western part of the state.

In 2010, Justin Moose, an extremist from Concord, North Carolina, was arrested for plotting to blow up a Planned Parenthood clinic. Moose, who claimed to represent the Army of God, also opposed the construction of a mosque near ground zero in New York. He called himself the “Christian counterpart of Osama Bin Laden.” Eventually, Moose pleaded guilty to disseminating information on how to make and use explosive devices.

In 2014, Frazier Glenn Miller, a career anti-Semite and former grand dragon of the Carolina Knights of the Ku Klux Klan, killed three people at a Jewish community center and a Jewish retirement home in Kansas. Decades ago, long before ISIS conceived of an Islamic State in Iraq and Syria, Miller devised a similar plan in the United States: an “all-white nation within the bounds of North and South Carolina.”

Among dozens of avowedly Christian, anti-Semitic, and right-wing terrorists cataloged by the Anti-Defamation League and the Southern Poverty Law Center, you’ll find many from these two states: Charles Robert Barefoot Jr., a North Carolina Klan leader who was convicted in 2012 on charges involving firearms, explosives, and violent conspiracy. Kody Brittingham, a Marine at Camp Lejeune who confessed to plotting the assassination of President Obama. Paul Chastain, a South Carolina militiaman who tried to acquire plastic explosives and threatened to kill federal officials. Steve Bixby, a violent activist from an anti-Semitic household, who gunned down two police officers in Abbeville, South Carolina. Daniel Schertz, a Klansman arrested in Greenville, South Carolina, and later convicted, on weapons charges involving racist bomb plots.

And then there’s Dylann Roof. After allegedly murdering nine black people in a Charleston, South Carolina, church this summer, Roof drove more than three hours north, to Shelby, North Carolina. Nobody stopped him at the state border. The boundary between North and South Carolina, like the boundary between Syria and Iraq, is a joke.

Today, Republican presidential candidates are climbing over one another in a race to block the entry of Syrian refugees. They’re doing this even though, among the nearly 800,000 refugees we’ve accepted since 9/11, not one has been convicted of—or has even been arrested for—plotting a terror attack in this country. (A few have been arrested for links to terrorism elsewhere.) Why do refugees have such a clean record? Because they have to go through an elaborate process: screening by U.N. evaluators, “biometric and biographic checks,” consultations with U.S. counterterrorism agencies, and an in-person interview with the Department of Homeland Security. On average, the process takes about a year and a half—or, in the case of Syrian refugees, about two years.

Terrorists from North Carolina encounter no such scrutiny. They just climb into their cars, cross the border, and proceed to Georgia, Kansas, or Colorado. They’re protected by Article IV of the Constitution, which, as interpreted by the U.S. Supreme Court, guarantees citizens “the right of free ingress into other States.” That’s why, among the 27 fatal terror attacks inflicted in this country since 9/11, 20 were committed by domestic right-wing extremists. (The other seven attacks were committed by domestic jihadists, not by foreign terrorist organizations.) Of the 77 people killed in these 27 incidents, two-thirds died at the hands of anti-abortion fanatics, “Christian Identity” zealots, white anti-Semites, or other right-wing militants.

This week’s carnage in Colorado brings the death toll from North Carolinian terrorists, including Eric Rudolph, to eight. That’s just one shy of the nine people murdered in Charleston. Throw in the work of a few lesser miscreants, and you’re looking at roughly 20 casualties inflicted by Carolina extremists.

That doesn’t make the Christian states of North and South Carolina anywhere near as dangerous as the Islamic State in Iraq and Syria. But it does make you wonder why, as we close our doors to refugees who have done us no harm, we pay so little attention to our enemies within.