Porter Ranch is an affluent neighborhood in the northwest region of the San Fernando Valley region of the city of Los Angeles, California. It is bounded by Brown's Canyon/Chatsworth on the south and west, Northridge on the south, and Granada Hills on the north and east. The Santa Susana Mountains, which separate the San Fernando and Santa Clarita valleys, lie to the north. The principal thoroughfares are Mason Ave., Corbin Ave., Porter Ranch Drive, Tampa Ave. and Reseda Blvd., running north-south, and Sesnon Blvd., Rinaldi St. and the Ronald Reagan Freeway (State Route 118), running east and west.