Just a few miles east of the Salton Sea, Slab City was an old Marine Base used for artillery training. They took the base away and now only the foundation slabs remain--hence, the name. It is literally shrub desert with about 300 various "homes," mostly RVs. I would guess that 90% are snowbirds, enjoying the warmth for free. Yes, FREE. No one claims jurisdiction over this area and so they call it the Last Free Place in America.
