Fallout: New California adds an all new story around a new player character, an adopted resident of Vault 18, embarking on a journey through the wastelands of the New California Republic's Cajon Pass. An unofficial prequel to New Vegas, FPB adds hours of new gameplay and a fully voiced stand alone campaign.
The California Wastelands - 2277 CE
Black Bear Mountain and Vault 18 is roughly 91 minutes from Downtown Los Angeles, if you're in the Highwayman.
The Explorable Areas have green circles.
Original Fallout 1 & 2 Areas are there for reference only, and are not visitable.