Why Do The British Drive On The Left?

In the Middle Ages you kept to the left for the simple reason that you never knew who you'd meet on the road in those days. Since most people are right-handed, swordsmen preferred to keep to the left in order to have their right arm nearer to an opponent and their scabbard further from him. Also, a right-handed person finds it easier to mount a horse from the left side of the horse, and it would be very difficult to do otherwise if wearing a sword (which would be worn on the left). It is safer to mount and dismount towards the side of the road, rather than in the middle of traffic, so if one mounts on the left, then the horse should be ridden on the left side of the road. This custom was given official sanction in 1300 AD, when Pope Boniface VIII invented the modern science of traffic control by declaring that pilgrims headed to Rome should keep left.

In the late 1700s, however, teamsters in France and the United States began hauling farm products in big wagons pulled by several pairs of horses. These wagons had no driver's seat, instead the driver sat on the left rear horse, so he could keep his right arm free to lash the team. Since he was sitting on the left, he naturally wanted everybody to pass on the left so he could look down and make sure he kept clear of the oncoming wagon's wheels. Therefore he kept to the right side of the road. The first known keep-right law in the U.S. was enacted in Pennsylvania in 1792, and in the ensuing years many states and Canadian provinces followed suit.

The trend among nations over the years has been toward driving on the right, 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. 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) when Samurai ruled the country, it wasn't until 1872 that this unwritten rule became more or less official.