It remains a curiosity and a bit of a historical mystery why we don't all drive on the same side of the road. The fact is that most people are right-handed; that's why, for much of history, drivers have stuck to the left. Ancient Romans using two-wheeled carriages are believed to have held the reins  with their right hands and a whip with their left; to avoid whipping the near drivers, they favored the left-hand side the road. It's also easier for right-handers to get on a horse from the left, so riders were attracted to that side to avoid the near traffic as they climbed on and off. Finally, knights  and the other drivers favored the left so they could do battle, if necessary, with their good hand. So why does most of the world travel on the right side today? Theories differ, but there's no doubt Napoleon was a major influence. The French have used the right since the late 18th century.  Some say that before the French Revolution, people in upper class drove their carriages on the left, forcing the _ to the right. During the violence, fearful rich people sought to mix with the peasantry by traveling on the right as well. Regardless of the origin, Napoleon brought right-hand traffic to the nations he conquered, including Russia, Switzerland and Germany. Hitler, in turn, ordered right-hand traffic in Czechoslovakia and Austria in the 1930s. Nations that escaped right-handed conquest, like Great Britain, kept their left-handed tradition. Who had a major effect on "keep-right" traffic law?
Ancient Romans Hitler Napoleon Austrians