Although there are now more efficient routes for traversing central California, State Route 99, also called the Golden State Highway, used to be the chosen one. It was the main thoroughfare from Mexico to Canada, and a straight shot through the Central Valley, California's 22,500-square-mile fertile crescent, which cranks out more than half of the nation's produce. Here, Dust Bowlers from the Plains sought jobs and arable soil during the Great Depression, and, more recently, Mexicans, about 14 million strong across the state, have proved integral to the area's agronomic success. In their communities throughout the Valley, they have also cultivated and perfected their very own version of Mexico's greatest culinary gift—the taco. Joe and I are on a 48-hour, 276-mile road trip down 99, from Sacramento to Bakersfield, to discover the very best of them.