Basically, every high school and CC in California has a designated CSU.
They officially define “Local” like this:
http://www.calstate.edu/sas/onestopkiosk/documents/CSULocalAdmission-ServiceAreas.pdf
As you can see, it is really specific - especially in more urban areas.
It is interesting for transfer applicants, CSULB looks back to the high school the applicant graduated from. I had never noticed that before.
UCs can choose a location to prefer - (certain high schools or zip codes that have been historically under-represented).
How that weighs in is very difficult to divine but, the areas aren’t typically proximate to the campus.
See item 14 on UCSBs list.
https://admissions.sa.ucsb.edu/applying/freshman/selection