In a five-part series this week on CTVNews.ca and CTV National News at 11, W5 Investigative Unit Managing Editor and Senior Correspondent Avery Haines follows the harrowing journeys of migrants who risk their lives crossing the Darien Gap and ride atop Mexico’s notorious 'Train of Death'. In this third installment, Haines travels across the Mexico-U.S. border.

The Mexico-U.S. border is the land crossing for migrants.

Hundreds die every year in the desert. It stretches almost 3,000 kilometres along four American states.

This map shows where there are fences and barriers, and where there are none.

I travelled the length of the border, in my search for migrant families I met six months ago when I trekked from Colombia to Panama in the Darien Gap for the W5 documentary, "."

Follow my journey across Mexico in this interactive map below, from the very eastern border to the far west, and an emotional reunion with two young girls we rescued in the jungle.

For a full-screen view of the map interactive, .