Ok we all know that us aussies have the steering on the right side of the car, of course we all know this because its the right side to be on :P

But i do have a serious question. Does anyone know why some countries i.e the US drives on the left side? I have been watching a few westerns lately and notice that the coach driver always sits on the right and the shotgun is always on the left.

Was there a reason for the driver location switch?