Chatsworth, westward from Andora Avenue. In 1821, after the Mexican War of Independence from Spain, the Mission San Fernando became part of Alta California, Mexico. In 1834, the Mexican government began redistributing the mission lands. In 1846, the Mexican land grant for Rancho Ex-Mission San Fernando was issued by Governor Pío Pico. It was bounded on the north by Rancho San Francisco and the Santa Susana Mountains, on the west by the Simi Hills, on the east by Rancho Tujunga, and on the south by the Montañas de Portesuelo (Santa Monica Mountains). The Rancho Ex-Mission San Fernando received a Federal land patent to retain ownership by the United States Public Land Commission in 1873 and was the single largest land grant in California. United States In 1869, the grantee's son, Eulogio F. de Celis, returned from Spain to Los Angeles. In 1874, the family sold their northern half of Rancho Ex-Mission San Fernando to northern Californians, California State Senator Charles Maclay and his partners George K. Porter, a San Francisco shoe manufacturer, and his brother Benjamin F. Porter. The Porters’ land was west of present-day Sepulveda Boulevard including most of Chatsworth, and the Maclay land was east of Sepulveda Boulevard. The Old Santa Susana Stage Road or Santa Susana Wagon Road continued in use as an alternative to the route along El Camino Viejo from 1861 to 1875, replacing the older road as the main route between Los Angeles and San Francisco. In 1876, the Southern Pacific Railroad opened a tunnel through the Newhall Pass, enabling rail connections from Los Angeles north to San Francisco, and rail travel soon replaced travel by stagecoach between Los Angeles and San Francisco. From this time, the stagecoach traffic to Santa Barbara once again used the coast route, and the Santa Susana Pass road was relegated to local traffic. The Chatsworth name, which hails from the stately Chatsworth House in England, was first recorded in 1888, when George R. Crow filed with the Los Angeles County Recorder's Office a map of the San Fernando Valley with a subdivision he called "Chatsworth Park." Later a W. B. Barber, the president of the San Fernando Valley Improvement Company who was believed to be from England, filed an additional map with the Recorder's Office called the "Plat of Chatsworth Park Townsite." A new wagon route bypassing the deteriorating Devil's Slide was opened in 1895. Initially called El