Recently I picked up a CA 52 shield which renewed my interest in revisiting some of the highways I used to frequent around San Diego circa 2011-2013. CA 52 by State Highway standards in California is relatively new having opened in pieces from 1970 through 2011. Below is a quick break down of the history of CA 52 along with applicable map scans:
https://www.gribblenation.org/2020/03/california-state-route-52.html