Walk In Their Shoes
Rarely does America see anything like this - a huge press of humanity streaming through Mexico, dreaming of life across the US border. Donald Trump, his administration paralysed over the $8 billion wall he needs to shut them out, calls them invaders.
So who are these people and what are they fleeing?
They've killed most of my family - my dad, my brother. We're running. Only God is with us – Tatyana, on the gang violence in her homeland Honduras
Now Tatyana and the other migrants have been warned, by none less than President Trump, that they risk being shot by US agents if they push too hard at the border.
She and her husband Ruben, with their two small children and another well on the way, press on.
I'm prepared to die trying to make a better future for my family - Ruben
Daniel, 13, is risking his life to buy a future. He is estranged from his mother, who sells drugs for a gang back home in El Salvador. His only choice there, he says, was to join a gang or run.
Too much violence and drugs, they kill you for nothing. I need to study, just study – Daniel
On the long road, rumours swirl.
I heard that the president will open the doors for us – Victor, a teenager from El Salvador
Over several weeks Foreign Correspondent follows the halting progress of two migrant caravans – one from Honduras, one from El Salvador – as they slowly wend their way through Mexico.
Most migrants say they are fleeing gang violence. Now they face a kidnap and murder threat from drug cartels as they make their way up La Ruta de la Muerte, or "Road of Death".
Constant movement equals constant fatigue. At 5 am a weary mother rouses her teary child when it's time to move again: Let's go, let's go -- No, no I don't want to, I want to stay here on my own!
Some give up on their American dream and turn back home.
We have come this far for nothing – Honduran man
But when Eric Campbell catches up with the thousands of migrants massing in Tijuana, near the US border, he finds that for a lucky few, fortune has swung their way.