Leaving the fields of the Imperial Valley, where a billion dollar industry produces over eighty percent of the winter vegetables in the U.S., I passed through miles of arid desert near Calexico.

Water from the Colorado River runs along Interstate 8 in a concrete canal on its way to turn dry land into verdant fields.

Scenes just a mile from fertile ground looked to me as barren as the moon; only one canal filled with scarce water made the difference between green and brown.

Arriving in Mexicali, I witnessed – in a microcosm – the economic interdependence the U.S. and Mexico share. Crossing the border on foot, I walked through the business district.

Nothing much for tourists here, but with thousands of commuters heading to Calexico each day, businesses had sprung up to serve them in their cars.

I spent part of the afternoon with Rebecca, Gerardo, and Hector who make and sell smoothies and coffee drinks and take orders and deliver them to drivers as they wait in traffic.

Hector told me how much he longed to work again in the United States. "If I can work here and make money, I'll have enough to go back. I have young children in California," he said.