It is necessarily true that a crime committed by someone in the United States without authorization is a crime that would not have been committed had that person not been in the country. It is similarly true that a home occupied by an undocumented immigrant (or a number of immigrants) is a home that would otherwise be available for use by someone else.

This does not mean, however, that immigrants are a central cause of crime or a primary driver of housing scarcity. But because the right views immigration as a central component to its political success next month, Republicans are eager to engage in such extrapolation — despite how consistently such extrapolations are shown to be baseless.

It is not true, for example, that the United States is experiencing a surge in violent crime, much less one driven by immigrants. Former president Donald Trump has claimed this repeatedly, offering it as an evolution of the foundational claim of his national political career: that immigrants crossing into the United States from Mexico are dangerous criminals who put native-born Americans at risk.

This has been debunked numerous times, including by demonstrating that immigrants to the United States are less likely to commit crimes than people born here. It is also not the case that there is a crisis in “migrant crime,” a term Trump adopted from his allies at Fox News, nor is it the case (as Trump and his allies alleged this week) that the Biden administration had allowed 13,000 murderers into the country.

While the number of immigrants seeking to come to the United States has increased during President Joe Biden’s term, crime — particularly the violent crime that Trump likes to amplify — is down over the past few years following a spike at the outset of the pandemic. A spike that began, you will recall, under Trump.

It is also not true that immigrants crossing into the United States illegally are a central conduit for the dangerous drug fentanyl. There has been a surge in overdoses linked to fentanyl — which, again, began under Trump. Since the drug frequently enters the United States across the southern border, Republicans have for years linked it to illegal immigration.

But unlike other drugs, such as marijuana, fentanyl is relatively easy to hide. That means it’s easier to smuggle in vehicles, rather than having to be carried by people walking across the border, which in turn means it’s faster to get it to distribution points. So most of the fentanyl seized at the border is found not on illegal border-crossers but at vehicle checkpoints.

Since it’s much easier for Americans to cross the border into the United States, American citizens are often recruited to do the smuggling. The New York Times just reported on this pattern, finding that more than 80 percent of those sentenced for crimes involving fentanyl smuggling are U.S. citizens.

During Tuesday night’s vice-presidential debate, Trump’s running mate, Sen. JD Vance (R-Ohio), attempted to blame high housing costs on immigrants.

“We have a lot of Americans that need homes,” he said. “We should be kicking out illegal immigrants who are competing for those homes, and we should be building more homes for the American citizens who deserve to be here.”

Pressed on the point by debate moderators, Vance promised to share what he described as “a Federal Reserve study” linking housing costs to immigration. Instead, Vance shared a portion of a speech in which the speaker suggested that immigration might help drive price inflation — but as economist Justin Wolfers pointed out, a portion Vance didn’t share said immigration may have helped lower inflation.

Vance is right that constraints on housing supply are a key factor in housing costs and availability. But those are generally a function of zoning rather than oversaturation. The people who would be building those new homes Vance seeks? Often immigrants.

Vance also claimed that the Biden administration’s policies were spurring a surge in illegal firearms.

“We’ve seen a massive influx in the number of illegal guns run by the Mexican drug cartels,” Vance claimed. “So that number, the amount of illegal guns in our country is higher today than it was 3½ years ago.”

This is backward. Cartels smuggle guns out of the United States, as CBS News and others have reported. In 2023, border agents stopped seven times as many weapons at the border — heading south — than they had in 2019.

The reason guns move from the United States to Mexico was summarized in a 2013 report on the subject.

“Mexico does not manufacture small arms, light weapons or ammunition in sizeable quantity,” it indicated. “Moreover, Mexico has some of the most restrictive gun legislation in the world.” Its neighbor to the north, though, makes guns readily available for citizens and immigrants alike.

In summary, then, it’s not true that violent crime is being pushed higher by immigrants, in part because Trump and his allies often wildly overstate the number of immigrants who’ve started living in the United States under the Biden administration. It’s not true that immigrants are the primary conduit for fentanyl into the country or for illegal firearms. It’s not true that immigrants are the central driver of housing costs — or even necessarily a significant one.

Again, we can cede the point raised at the beginning of this article, the one often raised by Republicans: An undocumented immigrant who commits a crime does result in a crime that wouldn’t have been committed had that undocumented immigrant not been in the United States.

It would be interesting, though, to consider how the right’s view of the situation might change if we simply replace the phrase “undocumented immigrant” with “gun.”