Slab city is a closed military base. When the military moved out they tore down the buildings leaving a bunch of concrete slabs, I'ts boondocking. A lot of the folks who camp there are, from what I understand, from the low end of the RV barrell, which is not to say some nice rigs don't park there from time to time. No authority governs it and I gather is a bit "wild" (As in bad lands)
That said, Never been there