Transcript for Trump: 'We have a crisis at the border. ... It's crazy'

see you a short time from now. You heard Jon Karl ask the vice president about that figure, 4,000 suspected terrorists have come to the country illegally. Tonight what are the numbers? Here's Matt Gutman with a reality check. Reporter: As he makes his case for a wall, president trump is painting a nightmare scenario of a border overrun. The crisis on our southern border -- and crisis it is. We have a crisis at the border. Criminals and gang members coming through. And it is a crisis. It's crazy. It's crazy. Reporter: In fact, the number of people crossing the border illegally has plunged over the past two decades. From 1.6 million people in 2001, when George W. Bush was president, to just over 400,000 in 2016 when Barack Obama was president to 361,000 last year. The president insists terrorists are pouring in from Mexico. We have terrorists coming through the southern border, because they find that's probably the easiest place to come through. They drive right in and they make a left. Reporter: That's not true, either. The president's own state department says there is "No credible information that any member of a terrorist group has traveled through Mexico to gain access to the United States." In fact, a recent state department report shows more concern about Canada, noting it is more often home to violent extremists aligned with ISIS or Al Qaeda. So, let's get to Matt Gutman, with us live tonight at the border. And tonight Americans are deeply divided over whether there is a national security crisis at the border. But advocates continue to point to a humanitarian crisis there. Reporter: That's right. An historically high number of families and children have been crossing into the United States, David. 22,000 children in the month of December alone. Some of them are presenting themselves to overwhelmed border patrol officials of 100 or more. And the policies coming out from the white house haven't exactly helped the problem, in fact, they've exacerbated it. Matt, thank you. ABC news will carry the president's address tonight and the democratic response. George and the team at 9 clng P.M. Eastern right here.

This transcript has been automatically generated and may not be 100% accurate.