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WASHINGTON — President Donald Trump on Tuesday addressed the nation from the Oval Office to make his case for a wall on the U.S.-Mexico border as the partial government shutdown stretched into its third week.

NBC News fact checked his prime-time speech as it happened.

Claim 1: The border is in crisis

America's immigration system is broken — that's something experts, advocates, and politicians across the aisle can agree on — but there's little evidence the southern border is experiencing a new state of emergency.

Though Trump has sounded the alarm over migrants arriving in record numbers, overall border crossings have actually been dropping for years. In the 1980s through the mid-2000s, the U.S. apprehended 1 million to 1.6 million immigrants caught illegally crossing the border each year. In fiscal year 2017, a combination of 415,517 people were apprehended after crossing the border illegally or were barred from entry, according to Customs and Border Protection. The White House has circulated a document indicating a projection for fiscal year 2019 of 600,000 apprehensions.

Earlier Tuesday, Vice President Mike Pence claimed that 60,000 people are now attempting to enter the country each month. According to CBP data from fiscal year 2019, around 51,000 people were apprehended at the southwestern border in October and November 2018 — an uptick from earlier months — and around 10,000 were deemed inadmissible, which means they approached a legal port of entry and were turned away.

To compare, in 2000, the southwestern border saw monthly apprehension totals of 73,458 – 223,305.

Trump and members of his administration routinely overstate the problem and need for a wall: Illegal immigration doesn’t cost as much as he says it does, and illegal drugs largely come through legal ports of entry, not unguarded parts of the border. Violence isn't spilling over, and terrorists aren’t being caught in droves trying to come in from Mexico.

And though Trump has focused on the border, illegal immigration in the U.S. is being driven by another factor: people who overstay their visas. More than 701,900 people overstayed their visas during fiscal year 2017, according to the Department of Homeland Security. People who overstay their visas usually enter the country from an airport, not from the border.

Claim 2: "Last month, 20,000 migrant children were illegally brought into the U.S., a dramatic increase."

It's hard to nail this number down exactly. According to data from the White House, in December, about 32,000 "family units" and 5,000 "unaccompanied minors" were apprehended at the border. But a "family unit" typically counts as a mother and child/children, so we don't how many of that 32,000 number are children and how many are adults.

Smuggling of children is exceedingly rare. In the first five months of fiscal year 2018, Department of Homeland Security data saw the number of child trafficking cases rise to 191. Still, that number accounted for roughly 0.5 percent of border crossings during the same period.

That said, it's fair to say the number of unaccompanied migrant children has been surging. Apprehensions of unaccompanied migrant children were up 21 percent from fiscal year 2017 to fiscal year 2018, and apprehensions of families traveling together was up 42 percent during the same period.

Crossings particularly surged in October and November, when 10,265 unaccompanied migrant children and 48,287 migrants traveling as families were apprehended at the border. Similarly high numbers of unaccompanied children were seen in 2014, but the numbers of families mark record highs, according to data going back to 2013.

Claim 3: Trump says the border is a "pipeline for vast quantities of illegal drugs."

The DEA says the vast majority of hard drugs from Mexican cartels come into the U.S. through legal ports of entry, which wouldn’t be affected by a wall.

According to a 2018 National Drug Threat Assessment by the DEA, Mexican drug cartels “transport the bulk of their drugs over the Southwest border through ports of entry (POEs) using passenger vehicles or tractor trailers. The drugs are typically secreted in hidden compartments when transported in passenger vehicles or commingled with legitimate goods when transported in tractor trailers."

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And then-Department of Homeland Security Secretary John Kelly said during a Senate hearing in April 2017 that illegal drug traffic “mostly comes through the ports of entry.”

It is true that hundreds of Americans die of drug overdoses involving heroin every week (the Centers for Disease Control and Prevention estimated about 300 per week in 2017), and that the majority of heroin sold in the U.S. is coming from Mexico. But again, that’s mostly coming through legal ports of entry. DEA said in 2018, for example: “A small percentage of all heroin seized by CBP along the land border was between Ports of Entry (POEs)."

Claim 4: "The wall will also be paid for indirectly by the great new trade deal."

Even if this was the case in the broadest of senses, the agreement doesn’t take effect until 2020 at the earliest. Trade experts have told fact-checkers that there's nothing in the new trade deal that earmarks funds for the border wall. Revenue raised by tariffs are federal dollars that must be appropriated by Congress.

What's more, the trade deal must still be ratified by legislators in the three countries involved.

Claim 5: "At the request of Democrats, it will be a steel barrier, instead of a concrete wall."

Democrats have rejected any wall, regardless of materials, on the grounds that it is bad policy and a bad moral message.

Trump offered Democrats a steel border fence instead of a concrete wall during recent shutdown negotiations, according to acting White House Chief of Staff Mick Mulvaney, something the White House viewed as a concession.

Claim 6: Trump notes that Senate Democrats have voted for border barriers in the past

This is true. Dozens of Democrats, including Senate Minority Leader Chuck Schumer, did vote for the Secure Fence Act of 2006, which authorized building a fence along about 700 miles of the border between the United States and Mexico.

Trump derided that fencing in 2016 as "such a little wall, such a nothing wall."

Claim 7: "Unlawful migration [is] fueled by our very strong economy."

In fact, the violence, drug cartels, gangs and poverty ravaging Central America have been driving people to the United States for years — and the unrelenting turmoil is still driving families to flee with their children.

Then-Homeland Security Secretary John Kelly noted the violence in a May 2017 speech at a forum sponsored by the Atlantic Council, a Washington-based foreign policy think tank.

“There’s corruption there. There’s terrible intimidation," Kelly said, adding that the cartels "are horrifically violent and they hold neighborhoods, cities in a grip of fear that includes police in many cases."

Claim 8: "Every week, 300 of our citizens are killed by heroin alone, 90 percent of which floods across from our southern border."

Nearly 16,000 people died in 2017 from heroin-involved overdoses, according to the Centers for Disease Control and Prevention.

The State Department estimates that at least 90 percent of America's heroin comes from Mexico, but the vast majority of that enters the U.S. through legal ports of entry.

Claim 9: "Women and children are the biggest victims, by far, of our broken immigration system."

Crossings by families with children, as well as crossings by unaccompanied children, have increased by 12,275 in October 2017 to 35,841 in November 2018. But the administration is currently working out a deal with Mexico to make asylum-seekers, including families with young children (but not children alone), wait in Mexico for months or even years while their asylum claims play out.

Far more crime occurs and harm comes to these families while waiting in Mexico than on the U.S. side.

Claim 10: "In the last two years, ICE officers made 266,000 arrests of aliens with criminal records including those charged or convicted of 100,000 assaults, 30,000 sex crimes, 4,000 violent killings."

Trump's numbers here are correct. Traffic violations and driving under the influence charges or convictions were also prevalent, and 125,683 of the charges or convictions were immigration-related crimes.

Claim 11: Trump says that "all Americans are hurt by uncontrolled, illegal migration," adding that "among those hardest hit are African-Americans and Hispanic Americans."

Trump suggested that minorities are among the hardest-hit by illegal immigration, although he did not offer evidence for that claim. There is some scholarly work to back up the claim that lower-skilled black men have suffered due to legal immigration. A 2007 study by Harvard economist George Borjas found "a strong correlation between immigration, black wages, black employment rates, and black incarceration rates.”

However, it's also worth noting that black and Hispanic voters overwhelmingly supported Hillary Clinton over Trump despite Trump's heavy emphasis on curbing both legal and illegal immigration during the 2016 campaign. Eighty-nine percent of black voters and 66 percent of Latinos backed Clinton.

Jane C. Timm reported from New York, and Carrie Dann from Washington.