5/27/16 BBC News
At the south-western tip of California, straddling the dirty trickle that is the Tijuana river, stands a wall – or rather a series of walls, fences and ditches.
This is the stuff of Donald Trump’s dreams, only his wall would be bigger and better of course, not to mention longer, stronger and vastly more expensive.
Between the fortifications, in what is effectively no-man’s land, a yellow line painted on the concrete marks the end of the mainland United States and the beginning of Mexico.
The border here owes its defences to Operation Gatekeeper, a controversial programme enacted in 1994 under President Bill Clinton which built barriers, added patrols and spruced up technology such as movement sensors.
All these years on, it appears to have worked, up to a point.
“It’s like water,” says border agent Shawn Moran as he drives the route near San Diego which he has patrolled for two decades. “They’re going to take the path of least resistance and right now there’s a lot of resistance out here.”