In Boston, the skyscrapers are so small that superheroes would look ridiculous zipping about them. Except maybe if they were college student superheroes. That'd be appropriate, too, what with all the colleges in the area.
Washington, DC isn't a real city, so it doesn't get any.
No supervillains have any interest in Detroit, so it doesn't need any.
Chicago has Gary Hobson.
At least movie Tony Stark mostly lives in LA.