Earlier quoted context omitted.
I seem to recall from a geography A-level course about 35 years ago in the UK that historically Los Angeles' spread was something to do with the city fathers offering incentives to adjoining communities to become part of Los Angeles - something like 'call yourself Los Angeles and we'll give you access to our water or electrical grid'. Is that right? A bit hazy after all this time.
Los Angeles had the water supply from Owens Lake, which enabled it to dictate terms to a lot of surrounding land whose owners wanted to develop (e.g. the San Fernando Valley). It's a huge, fairly flat coastal basin, and although the city limits don't cover the whole area, Los Angeles itself is 500 sq mi, which is larger than Phoenix, or 50% more land than New York City. It's really, really big.
I used to think the opening city shots in Blade Runner were an obvious exaggeration but apart from the Tyrell Corp building it looked pretty much the same.