Here's What Could Happen If Trump Tries To Close The Southern Border

President Donald Trump is once again threatening to close the U.S.-Mexico border. But what happens if the southern border actually was closed? While the president has failed to elaborate on how he'd go about closing the world's most frequently crossed international border, his sweeping threat could have serious consequences — if he's actually able to follow through with it, that is.

"We will be forced to close the Southern Border entirely if the Obstructionist Democrats do not give us the money to finish the Wall & also change the ridiculous immigration laws that our Country is saddled with," the president tweeted Friday. "Hard to believe there was a Congress & President who would approve!"

It's worth noting that this is the second time President Trump has threatened to close the country's southern border this year. In October, Trump threatened to "call up the U.S. Military and CLOSE OUR SOUTHERN BORDER" unless the Mexican government stopped a caravan of migrants attempting to seek asylum in the United States. This time, however, Trump's threat came in response to Democrats' refusal to cave in to his demand for billions in border wall funding. With the president and congressional leaders still unable to agree on a spending bill, hundreds of thousands of federal employees remain furloughed or forced to work without pay due to a partial government shutdown now in its eighth day.

In a series of later tweets also posted Friday, the president went on to frame a closure of the country's southern border as "a profit making operation" that could benefit the U.S. economy. "The United States looses soooo much money on Trade with Mexico under NAFTA, over 75 Billion Dollars a year (not including Drug Money which would be many times that amount), that I would consider closing the Southern Border a 'profit making operation,'” he tweeted. "We build a Wall or close the Southern Border."

Trump argued that in closing the U.S.-Mexico border he'd "bring our car industry back into the United States where it belongs" and return the country to an era "before so many of our companies and jobs were so foolishly sent to Mexico."

While it's unclear how exactly Trump would go about "clos(ing) the Southern Border entirely," some have said that such a threat is impossible. Immigration lawyer Leon Fresco told The Washington Post that the president can't close the border "entirely" because he legally cannot stop U.S. citizens from re-entering the country via the U.S.-Mexico border. What's more, Fresco noted that an attempt to close the border to foreigners who hold legal visas permitting them entrance to the United States would likely be challenged in court.

And while former President George W. Bush temporarily enacted a partial closure of the southern border in the aftermath of the 9/11 attacks, Fresco told The Post that Trump would have a tough time following suit as he tweeted that his motivation was political and not related to an imminent national security threat.

Others agree that Trump would, at the very least, be limited by the Constitution when it came to enacting any sort of border closure as the border is, by all definitions, always closed to anything but legal entry. "The key, as in the travel ban case, is that he can't do it in a way that violates constitutional rights, whether of those of a particular national origin, or of those non-citizens with sufficient connections to the U.S., to trigger due process protections," CNN reported University of Texas law professor Steve Vladeck (and regular contributor to the cable news outlet) said.

If, however, President Trump did manage to close the border "entirely," hundreds of thousands of people would likely be impacted. According to KPBS, roughly 100,000 people legally cross the border every day at the San Ysidro Port of Entry alone. Meaning any border closure could keep citizens, legal residents, and visa holders stranded.