It is a common misconception that driving on the left-hand side of the road is the "wrong" way. A comment by a poster on another thread reminded me of something i've read.
james_woods: The Jaguar XKE...and driving it on the wrong side of the road (http://www.jehovahs-witness.com/6/106004/1.ashx )
This is a mélange of several articles and my own comments, that explain the reasons for the difference in driving customs...
At one point, everybody who "drove" a cart or horse, used the English system of driving on the left. It was considered the most logical side to drive on for the following reasons:
In Roman times the shield was carried with the left hand and the sword with the right. The soldiers marched on the left, so they could protect their body with their shield and they were able to fight with their right hand. Battles are usually fought via the left wing, like in football.
A horse is mounted from the left. You swing the right leg over the horse's back. To make it easier for smaller people to mount the horse, special mounting stones were provided and put on the left side of the roads. Horses were harnessed one behind the other in England. The reins were drawn with the left hand, so you had to sit on the right and drive on the right in order to get a better view of the road. In adition logic dictated that when people passed each other on the road they should be in the best possible position to use their sword to protect themselves.
This practice of driving on the left, was formalised in a Papal Edict by Pope Benedict around 1300AD who told all his pilgrims to keep to the left. In the era of the French Revolution and rebellion against the established order of things, people figured, "hey, no pope is gonna tell ME what to do". The stage was set for a worldwide change.
Napoleon who was left-handed, preferred the new rebellious system of driving on the right. He used to draw his sword from right to left, he also fought his battles via the right wing. It had the advantage of making him successful as his enemies didn't expect this strategy. He imposed his soldiers to parade marching on the right and in every country he conquered he ordered that people had to drive on the right. Therefore, all of Napoleon's conquests had to change the side their carts and horses drove on.
Napoleon's conquests spread the new "rightism" to the Low Countries (Belgium, the Netherlands and Luxembourg), Switzerland, Germany, Poland, Russia and many parts of Spain and Italy. The states that had resisted Napoleon kept left – Britain, the Austro-Hungarian Empire and Portugal. This European division, between the left- and right-hand nations would remain fixed for more than 100 years, until after the First World War, when the French way crept into more and more European countries. An increase in horse traffic in London, forced the UK Government to introduce the General Highways Act of 1773 which contained a keep left recommendation. Before the Act, most countries drove on whichever side they chose, but after the Act, keeping left was imposed on all British colonies and territories. This Act became a law in Britain as part of the Highways Bill in 1835.
However, in the spirit of change and rebellion, the US after the War of Independence (1775–1783) arbitrarily changed from driving on the left to the right, because the keeping-left Law had become a symbol of British authority. In order to emphasise its difference from Britain, the US changed to right-side driving as did Canada due to the French influence.
Japan didn't change though. The origin of driving on the left 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. 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. The English minister to Japan achieved the coup of his career in 1859 when he persuaded his hosts to make keep-left the law in the future home of Toyota and Mitsubishi. This helps towards keeping Japanese cars cheaper in Britain than anywhere else, and helps i suppose to keep Britian from looking like an odd one out in a world of right-side drivers, haha.
On 3rd September 1967, the change from the left to the right side took place in Sweden, due to practical reasons. 82.9% voted “no” to the change but it went forward anyway. This was called "day H" (which stands for "höger" which means "right" in Swedish). Iceland followed in 1968.
In the 1960s, Great Britain also considered changing, but the country’s conservative powers did everything they could to nip the proposal in the bud. Furthermore, the fact that it would cost billions of pounds to change everything round wasn’t much of an incentive… Eventually, Britain dropped the idea.
Today driving on the left, is only practiced in 74 countries, including: Australia, India, United Kingdom, Ireland, Jamaica, Japan, Kenya, South Africa, New Zealand and a few others. Driving on the right is practiced in 166 countries.