There are different explanations for the use of right versus left. Some people believe that it is a natural tendency to walk or drive on the right. This is because most people are right-handed.
We can look back in history for reasons people move on the right or left of the road.Some people say that in Europe hundreds of years ago,people rode their hourses on the left.This way,their sword was between them in the opposite direction. They were ready to pull out their right arm.But there is evidence that people used the right side,too.In 1300,some say that Pope Boniface ordered pildgrims on the way to St.Peter's Basilica to stay to the right when they crossed a nearby bridge.