After annexing portions of Los Angeles and several other communities into what would become New Hope City, and looking up some dated census info, I came to the conclusion that New Hope City's population is at least 1 million people, and covers about 200 sq. Miles.
I decided that my old characters, C.A.T. Squad, will be based out of the San Pedro area of the New Hope City (and two of the characters will live in the near by estates). The only other hero groups that I have detailed/ran in the setting are in Los Angeles (Shadow Watch), Salton City (Salton City Stars), and elsewhere in the world. Considering how the superheroes in my game's setting tend to be low powered, it's very unlikely that a Justice League / Avengers like super-group would be popping up at every crime.