How Do Countries Choose Which Side They Drive On?

This past week, drivers in Samoa had to switch from driving on the right side of the road to driving on the wrong, er, left side. Since the switch was relatively sudden, all the buses now open onto the middle of the street! The Samoans say the switch was to end their dependence on American-made vehicles. Mental_floss takes a look at how other nations decided which side of the road to drive on. Some reasons seems silly in retrospect. Link