LHD London
United Kingdom
Okinawa & Japan
The Bahamas & Former British Dependencies
Why do some countries drive on the right and others on the left?
The most important factor seems to be the relative dominance of different types of animal-drawn carts and wagons. Most people are right-handed, which leads to a natural tendency to favour one side of the road or another depending on the means of transportation being used.
Many people who discuss this topic focus their attention on the role of wearing swords by mounted knights and samurai in the middle ages. However, the role of the sword may have been exaggerated by modern romantic ideas. Medieval road traffic would have been dominated by commoners on foot and transporting goods in carts, who would not have worn swords. The only people who would have routinely worn swords would have been the aristocracy and their troops, and when their wagons rolled, right-of-way was probably determined by rank, with commoners scattering into the ditches. Medieval knights were relatively few and far between on the roads, and even if they preferred to pass one another in a certain manner (probably more for ceremony and to show respect than out of a real perception of danger) the protocols they followed would not necessarily have translated into rules applicable to the entire population.
Walking: keep right. Most people appear to have a natural tendency to keep to the right. Right-handed swordsmen, however, may prefer to keep to the left in order to have their right arm nearer to a potential opponent, and to reduce the chance of the scabbard (worn on the left) hitting other people.
Riding a horse: keep left. 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 edge 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. Horsemen armed with swords prefer to keep left of each other in order that their sword arm is nearer their opponent — and, more often, to offer one’s right hand in friendship.