Why do some countries drive on the left? Because of the way carts were built and then not wanting to change.
There are 56 countries that drive on the left-hand side of the road, which is approximately 30%. With the exception of Japan and a few other countries, they are predominantly countries that used to be colonies of Britain. Britain is a left-hand drive country and it makes sense that it would impose the same system on its colonies. So, why do those 56 countries drive on the left and why do the other 140ish countries drive on the right?
The common story is that people started to walk on the left because most people were right handed and walking on the left would allow them to draw their sword to defend themselves. It would also mean that their scabbards wouldn’t collide. However, swords were expensive and it is unlikely that enough people would have had swords to make a left-right division necessary. It is said that Roman legions marched on the left of the road for the same reason, but one legion would be so unlikely to pass another legion that this is also probably not true. Most soldiers would march in the middle of the road. It is possible that among fighters, such as soldiers, or the Japanese samurai, a tradition of passing people on the left appeared, but there is no reason to think this would spread to ordinary people. A more likely answer is that most people are right-handed, which means their left leg is dominant. That means, when most people mount a horse, they do so from the left side of the horse. It would make sense to have the horse at the side of the road when you mount it, which would naturally put the horse pointing along the left side of the road.
A left-right system did become necessary when people were using carts. They could travel faster than people and without a system they might crash. However, again, this is viewing the problem with modern eyes. We have a lot of traffic running on narrow roads, so we need our system. Most carts would be running in open land or through towns that had fairly wide thoroughfares. As well as this, there would have been far less traffic than we have now, so it wouldn’t have been difficult to pass another vehicle on either side.
The left-hand drive system appears to have risen because of the way the carts were driven. Soldiers on horses may have used their right hands to hold a sword, but drivers of carts had to use their right hands to steer. This meant they would naturally sit on the right side of the cart. The right side of many carts also had a lever brake. Some larger carts were pulled by a team of horses, so the driver would sit on the last horse on the right-hand side to drive the cart. If the person is sitting on the right, it is natural to drive on the left because it gives you a greater field of view.
This system was enshrined in law in Britain in 1756 and since then all vehicles have driven on the left side of the road. This didn’t continue in France and it probably ended because of the French Revolution. Carts in France also drove on the left side of the road and the poor people walked on the right. It is said that after the revolution, the wealthy French aristocrats started driving on the right in order to hide among the peasants. It was seen as a way to break with the old and Robespierre put it into law in 1791. Then Napoleon started to conquer Europe and he took the right-hand drive system with him.
Most countries were already left-hand drive. It might have stayed this way if the American War of Independence hadn’t happened. The French military played a large part in the war and General Lafayette took the idea of driving on the right with him. The new country of the United States of America liked the idea of breaking with Britain. Canada didn’t stop driving on the left until 1920, (the French states were already right-hand drive) and they made the change because it was easier to drive on the same side as the USA. Slowly, the countries that were next to countries that drove on the right slowly transitioned to driving on the left. The countries that carried on driving on the left are either islands or ex-British colonies.
Japan is an interesting example. They drove on the left-hand side and may have been persuaded to change to the right-hand side when they were occupied by the Americans after World War 2. They didn’t because of their train system. In the end of the 19th century, Japan was rapidly modernizing and they wanted a new train system. Britain, the USA, and France all offered to build them one. Japan ended up choosing Britain and they got a train system where the trains drive on the left-hand side. It made sense for them to drive on the roads this way as well. And this is what I learned today.
Photo by Lina Kivaka: https://www.pexels.com/photo/cars-on-the-road-between-apartment-buildings-5624171/
Sources
https://books.google.co.uk/books?id=qfak8nsMNGIC&pg=PA16&lpg=PA16&hl=en#v=onepage&q&f=false
https://www.uk-car-discount.co.uk/news/why-uk-drivers-drive-on-left-explained
https://en.wikipedia.org/wiki/Left-_and_right-hand_traffic
https://www.history.com/news/why-do-some-countries-drive-on-the-left-side-of-the-road
https://www.linkedin.com/pulse/why-do-japanese-drive-left-side-road-vlad-levada/