This is 99% invisible.
I'm Roman Mars.
This week, Donald Trump returns to the White House, and he's promised on day one to begin carrying out the largest domestic deportation operation in American history.
Trump plans to mobilize federal and local law enforcement to remove millions of undocumented immigrants from the country.
But already he's facing pushback from cities and states across the country that have declared themselves sanctuaries and say they won't cooperate.
This is a fight we've had many times before.
And back in 2017, during Trump's first term, we aired a two part series exploring the origins of the sanctuary movement.
We thought this would be a good week to revisit that story.
Here it is.
In July 1980, a group of Salvadoran migrants crossed the border from Mexico into Arizona.
They walked over an isolated mountain range and halfway across a wide desert valley, there were more than two dozen of them, people who'd left behind lives and jobs to come to the United States.
They'd hired some guides to lead them on the journey.
Reporting our story this week is Delaney Hall.
And those guides had brought them to a largely uninhabited part of the border.
It was a vast, empty and fatally hot stretch of the Sonoran Desert.
The temperature the next day got up to around 112, 115 degrees out there.
It was deadly.
This is John Fife.
He's a Presbyterian minister from Tucson, which is a couple of hours from where the migrants crossed.
They were in the middle of the most desolate and deadly area of the desert.