The government's own data, instead, suggest just the opposite of what the president needs the country to believe in order to fulfill his chief campaign promise and build a border wall. “His speech basically repeated every falsehood, every misconception, and every untruth that has been stated about the border and illegal immigrant crime and national security threats involving immigration for the last several years,” says Alex Nowrasteh, a senior immigration policy analyst at libertarian think tank Cato Institute.

Take the president’s suggestion on Friday that a disproportionately high number of undocumented people make up the federal prison population. According to a Department of Justice report released last June, about 20 percent of the federal prison population in the first quarter of 2018 were “known or suspected aliens,” and 93 percent of them were in the country illegally. The Federal Bureau of Prisons told WIRED on Friday that "19.3 percent of the BOP's inmates have either unknown or non-US citizenship," which, of course, includes a far broader category of immigrants than only the undocumented ones.

But the demographics of the federal prison population are hardly a fair proxy for the country as a whole. As the DOJ’s report states, 90 percent of the incarcerated population in the US resides in state and local prisons, and the rate of undocumented people in state and local prisons is far harder to calculate, as few states report those statistics. In Texas, one state that does calculate these figures, a Cato report found that in 2015, "as a percentage of their respective populations, there were 50 percent fewer criminal convictions of illegal immigrants than of native-born Americans."

In addition, immigration offenses are themselves federal offenses. It stands to reason, then, that people serving time for immigration offenses would be overrepresented in the prisons where people serve time for immigration offenses. The DOJ report doesn’t state what percentage of undocumented immigrants are in federal prison for violence or drug charges. Neither did President Trump.

Then there’s the president’s insistence that Democrats are lying when they say ports of entry, and not the southern border, are most responsible for drug smuggling. But in November of 2018, the Drug Enforcement Administration reported exactly that. “The most common method employed by these [transnational criminal organizations] involves transporting illicit drugs through U.S. [ports of entry] in passenger vehicles with concealed compartments or commingled with legitimate goods on tractor trailers,” the report reads.

The president's bleak description of rampant violence along the border also stands in stark contrast to what the Federal Bureau of Investigation's statistics show, Nowrasteh says. According to FBI crime reports obtained by Cato, in 2017, the violent crime rate, property crime rate, and homicide rate were lower along border counties than they were in the United States writ large. Not only that, but according to Customs and Border Patrol, in 2018 gang members accounted for just .2 percent of all apprehensions at the border.

"Those numbers would be very different if there was a real invasion," Nowrasteh says.

Such willful distorting of data in the service of stoking fear about a group of people has scary historical precedents, says Jason Stanley, a philosophy professor at Yale University and author of the book How Fascism Works. "He's saying data doesn't matter. He’s saying, 'This is about my power,'" Stanley says. "It’s a sign of power that you can declare a national emergency without there being one."

Before President Trump even completed his address, he anticipated the ways in which that power may be checked. "We will have a national emergency, and we’ll then be sued," he said, expressing full confidence that the Supreme Court would eventually uphold his declaration.