Baja California is a peninsula in what was northwestern Mexico. Its land mass separates the Pacific Ocean on the west from the Gulf of California (or "Sea of Cortés") on the eastern coastline. In 2281, under orders from President Kimball, New California Republic Rangers were deployed to the area for what Chief Hanlon describes as "chasing ghosts". Some NCR troopers say "I heard the ranger vets are coming in from Baja. I've never seen one before, but I heard they chew nails and spit napalm."
Baja is mentioned in Fallout: New Vegas.