We had something similar to what you propose in Georgia many, many years ago - the "County Unit System". That got tossed to accomodate the growing power of Atlanta.
I don't recall if it was repealed or invalidated by one of our black-robed overlords. That happened way before my time.
Of course, I know a system like this would never fly. The leftists know they would lose. Their power is concentrated in large metro areas. Not metrosexual but it Seattles case it may be. 8-)