Plus, before skyscrapers and other sorts high density developments geography had an okay correlation with population density, but that is no longer the case anymore. There are often far more people in a single block in a city than on an entire knob out in the knobs, or an entire mountain in mountainous areas, etc. You can't easily "circle" just a floor or three of a single building on a 2D map with any accuracy, but to balance population density fairly you may have to consider problems like that.
With TV, radio, the internet, skyscrapers, and urban density, maybe we need a whole new solution for representative democracy than where physically you collect your snail mail?
I don't have any good theories on what should replace geography, but I do think geography is a problem we could eliminate by ignoring that variable.