Norm

Post WW3 radiation levels caused genetic changes in much of the population. 
There are those however entirely unaffected by the radiation, these are referred to as 'Norms'.
The rich were for the most part Norms, and decided to build New San Francisco. The old city was left in ruins except the prime sections along the bay, which they cleaned up. 
Destitute Norms along the Mutants remained in the ruins