It’s like a global driving riddle: Why is it that some countries drive on the left and some on the right? And furthermore, who decided which countries would choose each side?

While there might seem to be no rhyme or reason to the whole deal, there are historical explanations for these driver-side differences. Let’s explore who drives on which side of the street and why.

Why Drive On The Left Side?

To residents of countries where right-side driving is the norm, driving on the left-hand side seems downright dodgy. But you might be surprised to learn that there was a time when it was the universal standard.

As it turns out, the custom of driving on the left dates way back to Ancient Rome, when violence was a common occurrence when traveling by horse. Since most people are right-handed, the cautious horse-rider would want to be aligned so that if push came to shove, he would be ready to fight.

Back then, the sword was normally worn on the left, because it was easier to mount the horse from the left, using the right leg. This way, the scabbard faced away from potential enemies, but it allowed for the rider’s dominant hand to be ready to reach for the sword and get ready to fight. Clever, huh?

Why Drive On The Right Side?

The custom of driving on the right side gradually arose in a variety of different countries and for a variety of different reasons.

Perhaps the most plausible is that as transit advanced from single horses to carts drawn by multiple horses, traveling on the right made more sense if the “driver” was riding on the left hand side so that he could use his right hand to control the far horse, and it was easier to veer to the right to allow others to pass.

But one of the most interesting theories? In France, it used to be customary for the peasants to pass on the right and aristocrats to pass on the left. However, following the attack on Versailles, aristocrats who still had their heads were more inclined to keep a lower profile and stick with the peasants on the right. In 1794, right-side travel was officially made a rule in Paris.

Napoleon (said to be left-handed, by the way) spread the custom with his conquests, bringing right-side transport to a variety of countries including Belgium, Germany, Italy, Poland, and Spain. Eventually, it became the norm in Europe, aside from a few notable examples, including Great Britain.

Who Drives On The Left Side?

In terms of who drives on the left side, the biggest group is members of the British Empire. Britain bucked the trend, and in 1835, left-hand transit was made the rule. In general, countries that were part of the British Empire adhered to this rule as well. This explains why countries like India and former colonies in Africa still travel on the left.

Who Drives On The Right Side?

These days, about two thirds of the world travels on the right side: Most of Europe, North America, South America, and much of both Africa and Asia.

This includes the United States, of course. Why choose to travel on the right when the new country was formed? Some say that it was to further depart from British custom. Whether that’s true or not, it was made the law early on in the country and has remained in place ever since.

Look Both Ways!

The fact that not everyone drives on the same side of the road in different parts of the world can be awfully confusing. It has even been known to cause some terrible accidents. However, now you know that there are historical reasons why our wacky global driving system has evolved the way it has.