You must have wondered why in India, we drive on the left hand side and almost the whole world drives on the right hand side of the road. This driving habit perplexes the world, but there is a reason behind it.
Since most people are right-handed, swordsmen carried their sword on the right and the scabbard on the left. They preferred to travel on the left hand side so that in case of an encounter they have their right arm nearer to the opponent. Hence, in the past, almost everybody travelled on the left side of the
road because that was the most sensible option for feudal societies. Furthermore, a right-handed person finds it easier to mount and dismount a horse from the left side of the horse. So if one mounts on the left, then the horse should be ridden on the left side of the road.
However, in the late 1700s, France and United States took to right hand side. Wagons carrying farm products were pulled by several pairs of horses. These wagons had no
driver's seat and the driver sat on the left rear horse, so he could keep his right arm free to whip the horses. Moreover, he kept to the right side of the road so that he has a clue of the oncoming vehicle's
wheels.
Besides, the French Revolution of 1789 had a huge impact to right-hand travel in Europe. Before the Revolution, the aristocrats travelled on the left of the road, forcing common men to take right. But after the storming of the Bastille, aristocrats joined the peasants on the right. An official keep-right rule was introduced in Paris in 1794 and Denmark made compulsory in 1793.
Later, Napoleon's conquests spread the new 'rightism' to the other European countries except for countries that had resisted Napoleon. Hence Britain, the Austro-Hungarian Empire and Portugal continued to drive on the left hand side of the road.
Although left-driving Sweden ceded Finland to right-driving Russia after the Russo-Swedish War (1808-1809), Swedish law - including
traffic regulations - remained valid in Finland for another 50 years. It wasn't until 1858 that an Imperial Russian decree made Finland swap sides.
The trend among nations over the years has been toward driving on the right hand side, but Britain has done its best to stave off global homogenisation. With the expansion of travel and road building in the 1800s, traffic regulations were made in every country. Left-hand driving was made mandatory in Britain in 1835. Countries which were part of the British Empire followed suit. This is why to this very day, India, Australasia and the former British colonies in Africa go left. An exception to the rule, however, is Egypt.
Although Japan was never part of the British Empire, its traffic also goes to the left. Although the origin of this habit goes back to the Edo period (1603-1867), it wasn't until 1872 that this unwritten rule became more or less official. That was the year when Japan's first railway was introduced, built with technical aid from the British. Gradually, a massive network of railways and tram tracks was built and of course all trains and trams drove on the left-hand side. Still, it took another half century till in 1924 left-side driving was clearly written in a law.
In the early years of English colonisation of North America, English driving customs were followed and the colonies drove on the left. After gaining independence from England, however, they wanted to change to right-hand driving. The first law requiring drivers to keep right was passed in Pennsylvania in 1792 and similar laws were passed in New York in 1804 and New Jersey in 1813.