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Why Do Some Countries Drive on the Left?

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The Rule of the Road

It's basic common sense that if you have traffic driving in two directions on the same road, you need the flow of traffic organised so that everyone going in one direction keeps to the same side of the road. This is the rule of the road. Without it, head-on collisions would increase, and traffic would soon be gridlocked. Most of the world keeps its traffic on the right-hand side, yet there are a number of countries that drive on the left.

Just why do some countries drive on the left when the majority drive on the right? It's not as simple as an arbitrary decision, and there are a number of theories to explain the division. Here are some of the possible reasons, together with a list of those countries where they drive on the left.

Romans Drove on the Left

Durocornovium was a Roman settlement near the present-day town of Swindon in the UK. The Romans quarried stone at the site, and it is here that archaeologists found evidence to support the theory of the Romans driving on the left. Shallow ruts were found on one side of the track, deep grooves on the other. The deeper marks, caused by the heavily stone-laden carts leaving the quarry, were on the left side of the track.

Driving on the Left in Ancient Times

Driving on the left appears to be man's preferred driving side. Historians and archaeologists (see box right) have uncovered plenty of evidence to show that the ancient Romans and Greeks not only drove their carts and chariots on the left but also marched their armies on the left and required pedestrians to use the left-hand side.

But why did people choose the left, rather than the right?

Britain's First Keep Left Law

In 1756 the British Government passed a law requiring traffic to keep to the left on London Bridge. Up until that time it was custom, not law, that kept traffic on the left of the road.

Driving on the Left and Self-Defence

Most people are right-handed; hence they would carry a weapon in their right hand. When travelling, it makes sense to keep to the left so that if you meet someone on the road, and the stranger was unfriendly, you were both in a position to draw swords and fight. As people began to ride more, they could hold the horse's reins in their left hand and keep their right hand ready for trouble. For this reason, armies marched on the left and knights practised jousting on the left.

Travelling on the left made perfect sense in a violent society, and the habit remained throughout the world up until the eighteenth century. Then, a change to the right began.

Australian road sign reminding foreign visitors of which side of the road to drive on.

Australian road sign reminding foreign visitors of which side of the road to drive on.

Why the Switch From the Left to the Right?

Generations of travellers, riders and coach drivers had been keeping left. By the end of the eighteenth century, a change began. It wasn't because drivers were less likely to be attacked on the road (although that may have been true); it was because the type of trucks they used changed.

The traditional type of cart had a driver's seat at the front, and the driver could sit on the right-hand side of the seat and see what was coming on his right. However, the French and Americans, with wider roads, adopted heavier trucks with teams of horses. These wagons had no seat for the driver, and he had to ride postillion, mounted on the left rear horse. Being mounted in this position, he could use a whip in his right hand to control the horses. It made sense to drive on the right so that the driver could see oncoming traffic and avoid the wheels. Hence, the USA and France began to drive on the right.

Britain never adopted the new heavy wagons, perhaps because the streets in her towns were too narrow, so there was no need to change the rule of the road. As Britain started building an empire, the left-hand side rule was exported to new countries all over the world. The French introduced their rule of the road to their colonies. The divide became global.

Countries driving on the right shown red, countries driving on the left shown blue.

Countries driving on the right shown red, countries driving on the left shown blue.

Countries Driving on the Left Become a Minority

The decline of driving on the left gathered pace in the twentieth century. Many former British colonies switched to make it easier to cross borders with their right hand driving neighbours. Gradually, only Britain, a few of her former colonies and Japan were left driving on the left. Roughly two-thirds of the world drive on the right, the remaining one-third remaining on the left.

Chaos in Stockholm as the country switches from driving on the left to the right in 1967.

Chaos in Stockholm as the country switches from driving on the left to the right in 1967.

Why Don't Left Side Driving Countries Change?

The European Union would have liked Britain to fall into line with the rest of Europe and drive on the right. However, it was estimated about 20 years ago that this would cost in the region of £6 billion. In addition to the cost, it's unlikely that the British people would be in favour.

It's not unheard of for a country to change; the most recent change in Europe was Sweden. On "Dagen H" ("H Day"), 3 September 1967, the traffic changed sides, despite the public voting against the change over a period of 40 years previously. Although there was initial chaos, there were, in fact, fewer traffic accidents than usual.

Some countries have actually changed from right to left side driving. In 2009 for instance, Samoa became the first country for nearly 40 years to change its traffic side. The change was made to allow Samoans to buy cheaper imported left side drive (e.g., right-hand drive!) vehicles from nearby Australia, New Zealand and Japan.

Countries Which Drive on the Left




Solomon Islands


Antigua & Barbuda

Falkland Islands


South Africa

United Kingdom




Sri Lanka

US Virgin Islands




St Kitts & Nevis





St Helena





St Lucia





British Virgin Islands


New Zealand






Cayman Islands


Papua New Guinea


Channel Islands







Trinidad and Tobago




Turks & Caicos Islands

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2012 Judi Brown