Each day, a parade of trucks heads north out of the Southern California metropolis, grinding over the Tehachapis and descending into Kern County, one of the state's premier agricultural regions. The convoy is nearly a mirror image of the truck traffic heading the other way laden with commodities grown in the fertile Central Valley.
There is an important difference, however. Whereas the southbound trucks, bearing oranges, tomatoes, almonds, carrots, cotton and other valued products, are we...