Theories differ, but there's no doubt Napoleon was a major influence. The French have used the right since at least the late 18th century (there's evidence of a Parisian "keep-right" law dating to 1794). Some say that before the French Revolution, aristocrats drove their carriages on the left, forcing the peasantry to the right. Amid the upheaval, fearful aristocrats sought to blend in with the proletariat 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, preserved their left-handed tradition.
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