In 1859, the California Legislature appropriated $15,000 for improving an old wagon road through the Santa Susana Pass. Additional funding was provided by the Counties of Los Angeles and Santa Barbara. The outbreak of the American Civil War in 1861 disrupted mail service along the Butterfield Overland Mail's southern stagecoach route from St. Louis, Missouri via El Paso, Fort Yuma and Los Angeles and on to San Francisco via the Tejon Pass, which had begun its run in 1858. To compensate, the government contracted the Butterfield Company to carry mail between Los Angeles and San Francisco via the new wagon road over the Santa Susana Pass. The first overland mail stage run through the pass took place on April 6, 1861. The new route diverged from the Tejon Pass route at the north end of the Cahuenga Pass, following the old coast road (El camino Viejo, the former El Camino Real to San Buenaventura (Ventura) and Santa Barbara) as far as the Rancho Los Encinos before striking northwest across the San Fernando Valley toward the Santa Susana Pass.