Nearly 1.4 million undocumented immigrants from a staggering 177 countries traveled through Mexico to the United States from January to May, according to Mexico's National Institute of Migration.

Surges of illegal immigration "over brief periods of time" have happened in the past, said Mark Krikorian, executive director of the Center for Immigration Studies, but this "huge variety" of countries is unprecedented.

Considering there are 193 member states in the United Nations, nearly the entire world is taking advantage of the president's "open invite," he said. 

"There were always a few exotics, that's kind of my term. They call them OTMs, other than Mexicans, because there were so few of them that they lumped them all together," Krikorian told Fox News Digital. But President Biden "essentially invited mass illegal immigration by letting people get across the border, and word spreads, so you're getting people from everywhere."

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The White House could not immediately be reached for comment.

The influx of undocumented immigrants has overwhelmed the country's social services system, crowded school districts that are already bursting at the seams and flooded the streets with homeless encampments, Krikorian said. 

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There's also the hotly debated issue of crime. 

Statistically, studies have differed on whether there is a link between immigration and spikes in violence, although illegal immigrants have been charged with high-profile crimes, such as the murders of Rachel Morin in Maryland and Georgia student Laken Riley.

Some of the stats are "ambiguous," Krikorian said, but "it doesn't matter." 

Victims allegedly died at the hands of suspects "who shouldn't have been here (in the U.S.) in the first place," he said. "This is a direct result of Biden's invitation to people around the world to illegally migrate to the United States."

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Illegal immigration from Mexico into the U.S. is nothing new, and has ebbed and flowed over the years. "It's a perennial issue," as Krikorian described it.

But the global influx using the world's busiest corridor of illegal immigration – from Mexico into the U.S. – has already created a virtually irreversible situation in the country, according to Krikorian. 

Even if the Biden administration – or a new president – wanted to deport illegal immigrants, the sheer number of natives from countries create a complex roadblock. 

"Each country is going to have different requirements about what kind of travel documents do you need? Can you prove that they're from that country? Because a lot of illegal aliens throw their documents away, so they can just make up who they are," Krikorian said. 

"If someone is from Honduras but he says he's from Peru, what are you going to do?"

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Even logistically, with immigrants from 177 countries sneaking into the U.S., that's exponentially more flights than ever before and 177 different consular services and diplomatic agencies to deal with, Krikorian said.

And some countries may not even accept the undocumented immigrants back into the country, or will "slow walk" the process, he said. 

"Some countries would prefer we just keep them, so they'll make it difficult," he said. "They'll lose the paperwork, or that kind of stuff, and each one of those things is one more complication in trying to enforce the law."

The U.S. Immigration and Customs Enforcement (ICE) agency's non-detained docket has surged to over 7 million cases in fiscal year 2024, according to data obtained by Fox News. 

The non-detained docket, which the agency's website explains is part of its Alternatives to Detention program, provided case-management support to released migrants that ICE says has helped "support noncitizens compliance with release conditions" and "increased court appearance rates."

The situation exacerbated staffing issues, which have forced each ICE officer working the docket to be responsible for about 7,000 cases, on average.