This is a common problem in Los Angeles, as many parts of the city are defined separately for neighborhoods and postal codes. So, while places like Northridge, Hollywood, Studio City, Toluca Lake, West Los Angeles are all part of Los Angeles, places like Burbank, Glendale, Santa Monica, and West Hollywood are their own independent cities with their own mayors.The best way to distinguish between Los Angeles city and other incorporated cities in Los Angeles County is to get a Thomas Bros. or similar map. All of Los Angeles City is white on the map, while the other cities are different colors. Unincorporated county area is yellow. To this day, when I think of a place in the LA area, I think of its color on that map and I can tell if it s part of LA city or not.
Yes, Northridge is part of the Los Angeles city limits. That s just like a question someone asked me a long time ago about who is the mayor of Hollywood? (the honorary mayor is Johnny Grant) when I was a directory assistance operator. Although you are right, Northridge does have a council member for that district on the Los Angeles City Council; but only one mayor, Antonio Villaraigosa.
just out of curiosity, are you asking this question for professor michaud s poli sci class?