Unless it's Detroit, which is nearly in ruins. (Speaking of which, Super_Dave's "Ashes of the Motor City" is a Princess take on Detroit, getting on towards completion.)

But yes, the Pongamia Covens (or the Vocation counterpart the Upas Covens) aren't really big enough to control a major city. I envision them as an extended family out in the boondocks, or an Old Money aristocratic clan that has a county or two in their coils - prosperous and somewhat influential, but not serious power brokers....